document_title: Bacteria

question_text: when did the first bacteria appear on earth

question_tokens: when did the first bacteria appear on earth

root

text: Bacteria

text: Etymology

text: The word bacteria is the plural of the New Latin bacterium, which is the latinisation of the Greek βακτήριον (bakterion),[16] the diminutive of βακτηρία (bakteria), meaning "staff, cane",[17] because the first ones to be discovered were rod-shaped.[18][19]

tag: p

text: Origin and early evolution

text: The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life.[20][21] Although bacterial fossils exist, such as stromatolites, their lack of distinctive morphology prevents them from being used to examine the history of bacterial evolution, or to date the time of origin of a particular bacterial species. However, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage.[22] The most recent common ancestor of bacteria and archaea was probably a hyperthermophile that lived about 2.5 billion–3.2 billion years ago.[23][24]

text: Bacteria were also involved in the second great evolutionary divergence, that of the archaea and eukaryotes. Here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea.[25][26] This involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes, which are still found in all known Eukarya (sometimes in highly reduced form, e.g. in ancient "amitochondrial" protozoa). Later, some eukaryotes that already contained mitochondria also engulfed cyanobacteria-like organisms, leading to the formation of chloroplasts in algae and plants.[27][28] This is known as secondary endosymbiosis.

text: Morphology

text: Bacteria display a wide diversity of shapes and sizes, called morphologies. Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0.5–5.0 micrometres in length. However, a few species are visible to the unaided eye—for example, Thiomargarita namibiensis is up to half a millimetre long[29] and Epulopiscium fishelsoni reaches 0.7 mm.[30] Among the smallest bacteria are members of the genus Mycoplasma, which measure only 0.3 micrometres, as small as the largest viruses.[31] Some bacteria may be even smaller, but these ultramicrobacteria are not well-studied.[32]

text: Most bacterial species are either spherical, called cocci (sing. coccus, from Greek kókkos, grain, seed), or rod-shaped, called bacilli (sing. bacillus, from Latin baculus, stick).[33] Some bacteria, called vibrio, are shaped like slightly curved rods or comma-shaped; others can be spiral-shaped, called spirilla, or tightly coiled, called spirochaetes. A small number of other unusual shapes have been described, such as star-shaped bacteria.[34] This wide variety of shapes is determined by the bacterial cell wall and cytoskeleton, and is important because it can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids and escape predators.[35][36]

text: Many bacterial species exist simply as single cells, others associate in characteristic patterns: Neisseria form diploids (pairs), Streptococcus form chains, and Staphylococcus group together in "bunch of grapes" clusters. Bacteria can also group to form larger multicellular structures, such as the elongated filaments of Actinobacteria, the aggregates of Myxobacteria, and the complex hyphae of Streptomyces.[37] These multicellular structures are often only seen in certain conditions. For example, when starved of amino acids, Myxobacteria detect surrounding cells in a process known as quorum sensing, migrate towards each other, and aggregate to form fruiting bodies up to 500 micrometres long and containing approximately 100,000 bacterial cells.[38] In these fruiting bodies, the bacteria perform separate tasks; for example, about one in ten cells migrate to the top of a fruiting body and differentiate into a specialised dormant state called a myxospore, which is more resistant to drying and other adverse environmental conditions.[39]

text: Bacteria often attach to surfaces and form dense aggregations called biofilms, and larger formations known as microbial mats. These biofilms and mats can range from a few micrometres in thickness to up to half a metre in depth, and may contain multiple species of bacteria, protists and archaea. Bacteria living in biofilms display a complex arrangement of cells and extracellular components, forming secondary structures, such as microcolonies, through which there are networks of channels to enable better diffusion of nutrients.[40][41] In natural environments, such as soil or the surfaces of plants, the majority of bacteria are bound to surfaces in biofilms.[42] Biofilms are also important in medicine, as these structures are often present during chronic bacterial infections or in infections of implanted medical devices, and bacteria protected within biofilms are much harder to kill than individual isolated bacteria.[43]

text: Cellular structure

text: Intracellular structures

text: The bacterial cell is surrounded by a cell membrane which is made primarily of phospholipids. This membrane encloses the contents of the cell and acts as a barrier to hold nutrients, proteins and other essential components of the cytoplasm within the cell.[44] Unlike eukaryotic cells, bacteria usually lack large membrane-bound structures in their cytoplasm such as a nucleus, mitochondria, chloroplasts and the other organelles present in eukaryotic cells.[45] However, some bacteria have protein-bound organelles in the cytoplasm which compartmentalize aspects of bacterial metabolism,[46][47] such as the carboxysome.[48] Additionally, bacteria have a multi-component cytoskeleton to control the localisation of proteins and nucleic acids within the cell, and to manage the process of cell division.[49][50][51]

text: Many important biochemical reactions, such as energy generation, occur due to concentration gradients across membranes, creating a potential difference analogous to a battery. The general lack of internal membranes in bacteria means these reactions, such as electron transport, occur across the cell membrane between the cytoplasm and the outside of the cell or periplasm.[52] However, in many photosynthetic bacteria the plasma membrane is highly folded and fills most of the cell with layers of light-gathering membrane.[53] These light-gathering complexes may even form lipid-enclosed structures called chlorosomes in green sulfur bacteria.[54]

text: Bacteria do not have a membrane-bound nucleus, and their genetic material is typically a single circular bacterial chromosome of DNA located in the cytoplasm in an irregularly shaped body called the nucleoid.[55] The nucleoid contains the chromosome with its associated proteins and RNA. The phylum Planctomycetes[56] and candidate phylum Poribacteria[57] may be exceptions to the general absence of internal membranes in bacteria, because they appear to have a double membrane around their nucleoids and contain other membrane-bound cellular structures. Like all living organisms, bacteria contain ribosomes, often grouped in chains called polyribosomes, for the production of proteins, but the structure of the bacterial ribosome is different from that of eukaryotes and Archaea.[58] Bacterial ribosomes have a sedimentation rate of 70S (measured in Svedberg units): their subunits have rates of 30S and 50S. Some antibiotics bind specifically to 70S ribosomes and inhibit bacterial protein synthesis. Those antibiotics kill bacteria without affecting the larger 80S ribosomes of eukaryotic cells and without harming the host.

text: Some bacteria produce intracellular nutrient storage granules for later use, such as glycogen,[59] polyphosphate,[60] sulfur[61] or polyhydroxyalkanoates.[62] Certain bacterial species, such as the photosynthetic Cyanobacteria, produce internal gas vacuoles, vesicles which they use to regulate their buoyancy—allowing them to move up or down into water layers with different light intensities and nutrient levels.[63] The gas vacuoles are freely permeable to gas.[64] Intracellular membranes called chromatophores are also found in membranes of phototrophic bacteria. Used primarily for photosynthesis, they contain bacteriochlorophyll pigments and carotenoids. An early idea was that bacteria might contain membrane folds termed mesosomes, but these were later shown to be artefacts produced by the chemicals used to prepare the cells for electron microscopy. Inclusions are considered to be nonliving components of the cell that do not possess metabolic activity and are not bounded by membranes. The most common inclusions are glycogen, lipid droplets, crystals, and pigments. Volutin granules are cytoplasmic inclusions of complexed inorganic polyphosphate. These granules are called metachromatic granules due to their displaying the metachromatic effect; they appear red or blue when stained with the blue dyes methylene blue or toluidine blue.Microcompartments are widespread, membrane-bound organelles that are made of a protein shell that surrounds and encloses various enzymes. Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation. Magnetosomes are bacterial microcompartments, present in magnetotactic bacteria, that contain magnetic crystals.

text: Extracellular structures

text: In most bacteria, a cell wall is present on the outside of the cell membrane. The cell membrane and cell wall comprise the cell envelope. A common bacterial cell wall material is peptidoglycan (called "murein" in older sources), which is made from polysaccharide chains cross-linked by peptides containing D-amino acids.[65] Bacterial cell walls are different from the cell walls of plants and fungi, which are made of cellulose and chitin, respectively.[66] The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, and the antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan.[66] The cell wall is absent in L-form bacteria. The main pathogenic types are some species of Mycoplasma.

text: There are broadly speaking two different types of cell wall in bacteria, a thick one in the gram-positives and a thinner one in the gram-negatives. The names originate from the reaction of cells to the Gram stain, a long-standing test for the classification of bacterial species.[67]

text: Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Lipopolysaccharides, also called endotoxins, are composed of polysaccharides and lipid A that is responsible for much of the toxicity of gram-negative bacteria. Most bacteria have the gram-negative cell wall, and only the Firmicutes and Actinobacteria have the alternative gram-positive arrangement.[68] These two groups were previously known as the low G+C and high G+C gram-positive bacteria, respectively. These differences in structure can produce differences in antibiotic susceptibility; for instance, vancomycin can kill only gram-positive bacteria and is ineffective against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa.[69] If the bacterial cell wall is entirely removed, it is called a protoplast, whereas if it is partially removed, it is called a spheroplast. β-Lactam antibiotics, such as penicillin, inhibit the formation of peptidoglycan cross-links in the bacterial cell wall. The enzyme lysozyme, found in human tears, also digests the cell wall of bacteria and is the body's main defence against eye infections.

text: Acid-fast bacteria, such as Mycobacteria, are resistant to decolorisation by acids during staining procedures. The high mycolic acid content of Mycobacteria is responsible for the staining pattern of poor absorption followed by high retention. The most common staining technique used to identify acid-fast bacteria is the Ziehl-Neelsen stain or acid-fast stain, in which the acid-fast bacilli are stained bright-red and stand out clearly against a blue background. In many bacteria, an S-layer of rigidly arrayed protein molecules covers the outside of the cell.[70] This layer provides chemical and physical protection for the cell surface and can act as a macromolecular diffusion barrier. S-layers have diverse but mostly poorly understood functions, but are known to act as virulence factors in Campylobacter and contain surface enzymes in Bacillus stearothermophilus.[71]

text: Flagella are rigid protein structures, about 20 nanometres in diameter and up to 20 micrometres in length, that are used for motility. Flagella are driven by the energy released by the transfer of ions down an electrochemical gradient across the cell membrane.[72]

text: Fimbriae (sometimes called "attachment pili") are fine filaments of protein, usually 2–10 nanometres in diameter and up to several micrometres in length. They are distributed over the surface of the cell, and resemble fine hairs when seen under the electron microscope. Fimbriae are believed to be involved in attachment to solid surfaces or to other cells, and are essential for the virulence of some bacterial pathogens.[73] Pili (sing. pilus) are cellular appendages, slightly larger than fimbriae, that can transfer genetic material between bacterial cells in a process called conjugation where they are called conjugation pili or "sex pili" (see bacterial genetics, below).[74] They can also generate movement where they are called type IV pili (see movement, below).

text: Glycocalyx is produced by many bacteria to surround their cells, and varies in structural complexity: ranging from a disorganised slime layer of extracellular polymeric substances to a highly structured capsule. These structures can protect cells from engulfment by eukaryotic cells such as macrophages (part of the human immune system).[75] They can also act as antigens and be involved in cell recognition, as well as aiding attachment to surfaces and the formation of biofilms.[76]

text: The assembly of these extracellular structures is dependent on bacterial secretion systems. These transfer proteins from the cytoplasm into the periplasm or into the environment around the cell. Many types of secretion systems are known and these structures are often essential for the virulence of pathogens, so are intensively studied.[77]

text: Endospores

text: Certain genera of gram-positive bacteria, such as Bacillus, Clostridium, Sporohalobacter, Anaerobacter, and Heliobacterium, can form highly resistant, dormant structures called endospores.[78] In almost all cases, one endospore is formed and this is not a reproductive process, although Anaerobacter can make up to seven endospores in a single cell.[79] Endospores have a central core of cytoplasm containing DNA and ribosomes surrounded by a cortex layer and protected by an impermeable and rigid coat. Dipicolinic acid is a chemical compound that composes 5% to 15% of the dry weight of bacterial spores. It is implicated as responsible for the heat resistance of the endospore.

text: Endospores show no detectable metabolism and can survive extreme physical and chemical stresses, such as high levels of UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure, and desiccation.[80] In this dormant state, these organisms may remain viable for millions of years,[81][82] and endospores even allow bacteria to survive exposure to the vacuum and radiation in space.[83] According to scientist Dr. Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth—and we know they're very hardened to radiation."[84] Endospore-forming bacteria can also cause disease: for example, anthrax can be contracted by the inhalation of Bacillus anthracis endospores, and contamination of deep puncture wounds with Clostridium tetani endospores causes tetanus.[85]

text: Metabolism

text: Bacteria exhibit an extremely wide variety of metabolic types.[86] The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy, but these traits often do not correspond with modern genetic classifications.[87] Bacterial metabolism is classified into nutritional groups on the basis of three major criteria: the kind of energy used for growth, the source of carbon, and the electron donors used for growth. An additional criterion of respiratory microorganisms are the electron acceptors used for aerobic or anaerobic respiration.[88]

text:
Nutritional types in bacterial metabolism

Nutritional type
Source of energy
Source of carbon
Examples

 Phototrophs
Sunlight
 Organic compounds (photoheterotrophs) or carbon fixation (photoautotrophs)
 Cyanobacteria, Green sulfur bacteria, Chloroflexi, or Purple bacteria

 Lithotrophs
Inorganic compounds
 Organic compounds (lithoheterotrophs) or carbon fixation (lithoautotrophs)
 Thermodesulfobacteria, Hydrogenophilaceae, or Nitrospirae

 Organotrophs
Organic compounds
 Organic compounds (chemoheterotrophs) or carbon fixation (chemoautotrophs)
 Bacillus, Clostridium or Enterobacteriaceae

tag: table

text: Carbon metabolism in bacteria is either heterotrophic, where organic carbon compounds are used as carbon sources, or autotrophic, meaning that cellular carbon is obtained by fixing carbon dioxide. Heterotrophic bacteria include parasitic types. Typical autotrophic bacteria are phototrophic cyanobacteria, green sulfur-bacteria and some purple bacteria, but also many chemolithotrophic species, such as nitrifying or sulfur-oxidising bacteria.[89] Energy metabolism of bacteria is either based on phototrophy, the use of light through photosynthesis, or based on chemotrophy, the use of chemical substances for energy, which are mostly oxidised at the expense of oxygen or alternative electron acceptors (aerobic/anaerobic respiration).

text: Bacteria are further divided into lithotrophs that use inorganic electron donors and organotrophs that use organic compounds as electron donors. Chemotrophic organisms use the respective electron donors for energy conservation (by aerobic/anaerobic respiration or fermentation) and biosynthetic reactions (e.g., carbon dioxide fixation), whereas phototrophic organisms use them only for biosynthetic purposes. Respiratory organisms use chemical compounds as a source of energy by taking electrons from the reduced substrate and transferring them to a terminal electron acceptor in a redox reaction. This reaction releases energy that can be used to synthesise ATP and drive metabolism. In aerobic organisms, oxygen is used as the electron acceptor. In anaerobic organisms other inorganic compounds, such as nitrate, sulfate or carbon dioxide are used as electron acceptors. This leads to the ecologically important processes of denitrification, sulfate reduction, and acetogenesis, respectively.

text: Another way of life of chemotrophs in the absence of possible electron acceptors is fermentation, wherein the electrons taken from the reduced substrates are transferred to oxidised intermediates to generate reduced fermentation products (e.g., lactate, ethanol, hydrogen, butyric acid). Fermentation is possible, because the energy content of the substrates is higher than that of the products, which allows the organisms to synthesise ATP and drive their metabolism.[90][91]

text: These processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and dimethylmercury) in the environment.[92] Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves.

text: Lithotrophic bacteria can use inorganic compounds as a source of energy. Common inorganic electron donors are hydrogen, carbon monoxide, ammonia (leading to nitrification), ferrous iron and other reduced metal ions, and several reduced sulfur compounds. In unusual circumstances, the gas methane can be used by methanotrophic bacteria as both a source of electrons and a substrate for carbon anabolism.[93] In both aerobic phototrophy and chemolithotrophy, oxygen is used as a terminal electron acceptor, whereas under anaerobic conditions inorganic compounds are used instead. Most lithotrophic organisms are autotrophic, whereas organotrophic organisms are heterotrophic.

text: In addition to fixing carbon dioxide in photosynthesis, some bacteria also fix nitrogen gas using the enzyme nitrogenase. This environmentally important trait can be found in most bacteria of the metabolic types listed above.[94]

text: Regardless of the type of metabolic process they employ, the majority of bacteria are able to take in raw materials only in the form of relatively small molecules, which enter the cell by diffusion or through molecular channels in cell membranes. The Planctomycetes are the exception (as they are in possessing membranes around their nuclear material). It has recently been shown that Gemmata obscuriglobus is able to take in large molecules via a process that in some ways resembles endocytosis, the process used by eukaryotic cells to engulf external items.[30][95]

text: Growth and reproduction

text: Unlike in multicellular organisms, increases in cell size (cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction.[96] Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes.[97] In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Myxobacteria and aerial hyphae formation by Streptomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.

text: In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media, such as agar plates, are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.[99]

text: Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and cyanobacterial) blooms that often occur in lakes during the summer.[100] Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomyces that inhibit the growth of competing microorganisms.[101] In nature, many organisms live in communities (e.g., biofilms) that may allow for increased supply of nutrients and protection from environmental stresses.[42] These relationships can be essential for growth of a particular organism or group of organisms (syntrophy).[102]

text: Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced.[103] The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport.[104] The final phase is the death phase where the bacteria run out of nutrients and die.

text: Genomes and chromosomes

text: The genomes of thousands of bacterial species have been sequenced, with at least 9,000 sequences completed and more than 42,000 left as "permanent" drafts (as of Sep 2016).[105]

text: Chromosome. Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs (bp) in the endosymbiotic bacteria Candidatus Carsonella ruddii,[106] to 12,200,000 base pairs (12.2 Mbp) in the soil-dwelling bacteria Sorangium cellulosum.[107] The genes in bacterial genomes are usually a single continuous stretch of DNA and although several different types of introns do exist in bacteria, these are much rarer than in eukaryotes.[108]

text: Multiple chromosomes have been found in the genus Vibrio. For instance, Vibrio cholerae, the cause of cholera, and V. parahaemolyticus, have 2 chromosomes each.[109] In fact, 10% of all sequenced bacterial genomes are estimated to have 2 or more chromosomes.[109]

text: Some bacteria, e.g. Borrelia burgdorferi, the cause of Lyme disease, contains a single linear chromosome and several linear and circular plasmids.[110][111] The chromosome of Streptomyces lividans is linear too[112] and there is evidence that this is true in most species of Streptomyces.[110]

text: Plasmids are small extra-chromosomal DNAs that may contain genes for antibiotic resistance, enzymes that degrade unusual organic substrates, toxins that kill other bacteria, or virulence factors.[113] Plasmids replicate independently of chromosomes and often encode partition systems that ensure each daughter cell receives a copy of the plasmid following cell division. Partition systems are also encoded by most bacterial chromosomes. Plasmids that are maintained at a high copy number per cell typically lack partition systems because plasmids will randomly assort to both daughter cells.[114]

text: Genetics

text: Bacteria, as asexual organisms, inherit an identical copy of the parent's genes and are clonal. However, all bacteria can evolve by selection on changes to their genetic material DNA caused by genetic recombination or mutations. Mutations come from errors made during the replication of DNA or from exposure to mutagens. Mutation rates vary widely among different species of bacteria and even among different clones of a single species of bacteria.[115] Genetic changes in bacterial genomes come from either random mutation during replication or "stress-directed mutation", where genes involved in a particular growth-limiting process have an increased mutation rate.[116]

text: DNA transfer

text: Some bacteria also transfer genetic material between cells. This can occur in three main ways. First, bacteria can take up exogenous DNA from their environment, in a process called transformation. Genes can also be transferred by the process of transduction, when the integration of a bacteriophage introduces foreign DNA into the chromosome. The third method of gene transfer is conjugation, whereby DNA is transferred through direct cell contact.

text: Transduction of bacterial genes by bacteriophage is a consequence of infrequent errors during intracellular assembly of virus particles. Conjugation, in the much-studied E. coli system, is determined by plasmid genes that encode the machinery necessary to transfer a new copy of the plasmid DNA from one bacterial host to another. It is seldom that a conjugative plasmid integrates into the host bacterial chromosome and subsequently transfers part of the host bacterial DNA to another bacterium.

text: Transformation, unlike transduction or conjugation, depends on numerous bacterial gene products that specifically interact to perform this complex process.[117] In order for a bacterium to bind, take up and recombine donor DNA into its own chromosome, it must first enter a special physiological state termed competence (see Natural competence). In Bacillus subtilis, about 40 genes are required for the development of competence.[118] The length of DNA transferred during B. subtilis transformation can be between a third of a chromosome up to the whole chromosome.[119][120] Transformation appears to be common among bacterial species, and thus far at least 60 species are known to have the natural ability to become competent for transformation.[121] The development of competence in nature is usually associated with stressful environmental conditions, and seems to be an adaptation for facilitating repair of DNA damage in recipient cells.[122]

text: In ordinary circumstances, transduction, conjugation, and transformation involve transfer of DNA between individual bacteria of the same species, but occasionally transfer may occur between individuals of different bacterial species and this may have significant consequences, such as the transfer of antibiotic resistance.[123] In such cases, gene acquisition from other bacteria or the environment is called horizontal gene transfer and may be common under natural conditions.[124] Gene transfer is particularly important in antibiotic resistance as it allows the rapid transfer of resistance genes between different pathogens.[125]

text: Bacteriophages

text: Bacteriophages are viruses that infect bacteria. Many types of bacteriophage exist, some simply infect and lyse their host bacteria, while others insert into the bacterial chromosome. A bacteriophage can contain genes that contribute to its host's phenotype: for example, in the evolution of Escherichia coli O157:H7 and Clostridium botulinum, the toxin genes in an integrated phage converted a harmless ancestral bacterium into a lethal pathogen.[126] Bacteria resist phage infection through restriction modification systems that degrade foreign DNA,[127] and a system that uses CRISPR sequences to retain fragments of the genomes of phage that the bacteria have come into contact with in the past, which allows them to block virus replication through a form of RNA interference.[128][129] This CRISPR system provides bacteria with acquired immunity to infection.

text: Behaviour

text: Secretion

text: Bacteria frequently secrete chemicals into their environment in order to modify it favourably. The secretions are often proteins and may act as enzymes that digest some form of food in the environment.

text: Bioluminescence

text: A few bacteria have chemical systems that generate light. This bioluminescence often occurs in bacteria that live in association with fish, and the light probably serves to attract fish or other large animals.[130]

text: Multicellularity

text: Bacteria often function as multicellular aggregates known as biofilms, exchanging a variety of molecular signals for inter-cell communication, and engaging in coordinated multicellular behaviour.[131][132]

text: The communal benefits of multicellular cooperation include a cellular division of labour, accessing resources that cannot effectively be used by single cells, collectively defending against antagonists, and optimising population survival by differentiating into distinct cell types.[131] For example, bacteria in biofilms can have more than 500 times increased resistance to antibacterial agents than individual "planktonic" bacteria of the same species.[132]

text: One type of inter-cellular communication by a molecular signal is called quorum sensing, which serves the purpose of determining whether there is a local population density that is sufficiently high that it is productive to invest in processes that are only successful if large numbers of similar organisms behave similarly, as in excreting digestive enzymes or emitting light.

text: Quorum sensing allows bacteria to coordinate gene expression, and enables them to produce, release and detect autoinducers or pheromones which accumulate with the growth in cell population.[133]

text: Movement

text: Many bacteria can move using a variety of mechanisms: flagella are used for swimming through fluids; bacterial gliding and twitching motility move bacteria across surfaces; and changes of buoyancy allow vertical motion.[134]

text: Swimming bacteria frequently move near 10 body lengths per second and a few as fast as 100. This makes them at least as fast as fish, on a relative scale.[135]

text: In bacterial gliding and twitching motility, bacteria use their type IV pili as a grappling hook, repeatedly extending it, anchoring it and then retracting it with remarkable force (>80 pN).[136]

text: Our observations redefine twitching motility as a rapid, highly organized mechanism of bacterial translocation by which Pseudomonas aeruginosa can disperse itself over large areas to colonize new territories. It is also now clear, both morphologically and genetically, that twitching motility and social gliding motility, such as occurs in Myxococcus xanthus, are essentially the same process.

text: Flagella are semi-rigid cylindrical structures that are rotated and function much like the propeller on a ship. Objects as small as bacteria operate a low Reynolds number and cylindrical forms are more efficient than the flat, paddle-like, forms appropriate at human-size scale.[138]

text: Bacterial species differ in the number and arrangement of flagella on their surface; some have a single flagellum (monotrichous), a flagellum at each end (amphitrichous), clusters of flagella at the poles of the cell (lophotrichous), while others have flagella distributed over the entire surface of the cell (peritrichous). The bacterial flagella is the best-understood motility structure in any organism and is made of about 20 proteins, with approximately another 30 proteins required for its regulation and assembly.[134] The flagellum is a rotating structure driven by a reversible motor at the base that uses the electrochemical gradient across the membrane for power.[139] This motor drives the motion of the filament, which acts as a propeller.

text: Many bacteria (such as E. coli) have two distinct modes of movement: forward movement (swimming) and tumbling. The tumbling allows them to reorient and makes their movement a three-dimensional random walk.[140] (See external links below for link to videos.) The flagella of a unique group of bacteria, the spirochaetes, are found between two membranes in the periplasmic space. They have a distinctive helical body that twists about as it moves.[134]

text: Motile bacteria are attracted or repelled by certain stimuli in behaviours called taxes: these include chemotaxis, phototaxis, energy taxis, and magnetotaxis.[141][142][143] In one peculiar group, the myxobacteria, individual bacteria move together to form waves of cells that then differentiate to form fruiting bodies containing spores.[39] The myxobacteria move only when on solid surfaces, unlike E. coli, which is motile in liquid or solid media.

text: Several Listeria and Shigella species move inside host cells by usurping the cytoskeleton, which is normally used to move organelles inside the cell. By promoting actin polymerisation at one pole of their cells, they can form a kind of tail that pushes them through the host cell's cytoplasm.[144]

text: Classification and identification

text: Classification seeks to describe the diversity of bacterial species by naming and grouping organisms based on similarities. Bacteria can be classified on the basis of cell structure, cellular metabolism or on differences in cell components, such as DNA, fatty acids, pigments, antigens and quinones.[99] While these schemes allowed the identification and classification of bacterial strains, it was unclear whether these differences represented variation between distinct species or between strains of the same species. This uncertainty was due to the lack of distinctive structures in most bacteria, as well as lateral gene transfer between unrelated species.[146] Due to lateral gene transfer, some closely related bacteria can have very different morphologies and metabolisms. To overcome this uncertainty, modern bacterial classification emphasises molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridisation, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene.[147] Classification of bacteria is determined by publication in the International Journal of Systematic Bacteriology,[148] and Bergey's Manual of Systematic Bacteriology.[149] The International Committee on Systematic Bacteriology (ICSB) maintains international rules for the naming of bacteria and taxonomic categories and for the ranking of them in the International Code of Nomenclature of Bacteria.

text: The term "bacteria" was traditionally applied to all microscopic, single-cell prokaryotes. However, molecular systematics showed prokaryotic life to consist of two separate domains, originally called Eubacteria and Archaebacteria, but now called Bacteria and Archaea that evolved independently from an ancient common ancestor.[1] The archaea and eukaryotes are more closely related to each other than either is to the bacteria. These two domains, along with Eukarya, are the basis of the three-domain system, which is currently the most widely used classification system in microbiology.[150] However, due to the relatively recent introduction of molecular systematics and a rapid increase in the number of genome sequences that are available, bacterial classification remains a changing and expanding field.[4][151] For example, a few biologists argue that the Archaea and Eukaryotes evolved from gram-positive bacteria.[152]

text: The identification of bacteria in the laboratory is particularly relevant in medicine, where the correct treatment is determined by the bacterial species causing an infection. Consequently, the need to identify human pathogens was a major impetus for the development of techniques to identify bacteria.

text: The Gram stain, developed in 1884 by Hans Christian Gram, characterises bacteria based on the structural characteristics of their cell walls.[67] The thick layers of peptidoglycan in the "gram-positive" cell wall stain purple, while the thin "gram-negative" cell wall appears pink. By combining morphology and Gram-staining, most bacteria can be classified as belonging to one of four groups (gram-positive cocci, gram-positive bacilli, gram-negative cocci and gram-negative bacilli). Some organisms are best identified by stains other than the Gram stain, particularly mycobacteria or Nocardia, which show acid-fastness on Ziehl–Neelsen or similar stains.[153] Other organisms may need to be identified by their growth in special media, or by other techniques, such as serology.

text: Culture techniques are designed to promote the growth and identify particular bacteria, while restricting the growth of the other bacteria in the sample. Often these techniques are designed for specific specimens; for example, a sputum sample will be treated to identify organisms that cause pneumonia, while stool specimens are cultured on selective media to identify organisms that cause diarrhoea, while preventing growth of non-pathogenic bacteria. Specimens that are normally sterile, such as blood, urine or spinal fluid, are cultured under conditions designed to grow all possible organisms.[99][154] Once a pathogenic organism has been isolated, it can be further characterised by its morphology, growth patterns (such as aerobic or anaerobic growth), patterns of hemolysis, and staining.

text: As with bacterial classification, identification of bacteria is increasingly using molecular methods. Diagnostics using DNA-based tools, such as polymerase chain reaction, are increasingly popular due to their specificity and speed, compared to culture-based methods.[155] These methods also allow the detection and identification of "viable but nonculturable" cells that are metabolically active but non-dividing.[156] However, even using these improved methods, the total number of bacterial species is not known and cannot even be estimated with any certainty. Following present classification, there are a little less than 9,300 known species of prokaryotes, which includes bacteria and archaea;[157] but attempts to estimate the true number of bacterial diversity have ranged from 107 to 109 total species—and even these diverse estimates may be off by many orders of magnitude.[158][159]

text: Interactions with other organisms

text: Despite their apparent simplicity, bacteria can form complex associations with other organisms. These symbiotic associations can be divided into parasitism, mutualism and commensalism. Due to their small size, commensal bacteria are ubiquitous and grow on animals and plants exactly as they will grow on any other surface. However, their growth can be increased by warmth and sweat, and large populations of these organisms in humans are the cause of body odour.

text: Predators

text: Some species of bacteria kill and then consume other microorganisms, these species are called predatory bacteria.[162] These include organisms such as Myxococcus xanthus, which forms swarms of cells that kill and digest any bacteria they encounter.[163] Other bacterial predators either attach to their prey in order to digest them and absorb nutrients, such as Vampirovibrio chlorellavorus,[164] or invade another cell and multiply inside the cytosol, such as Daptobacter.[165] These predatory bacteria are thought to have evolved from saprophages that consumed dead microorganisms, through adaptations that allowed them to entrap and kill other organisms.[166]

text: Mutualists

text: Certain bacteria form close spatial associations that are essential for their survival. One such mutualistic association, called interspecies hydrogen transfer, occurs between clusters of anaerobic bacteria that consume organic acids, such as butyric acid or propionic acid, and produce hydrogen, and methanogenic Archaea that consume hydrogen.[167] The bacteria in this association are unable to consume the organic acids as this reaction produces hydrogen that accumulates in their surroundings. Only the intimate association with the hydrogen-consuming Archaea keeps the hydrogen concentration low enough to allow the bacteria to grow.

text: In soil, microorganisms that reside in the rhizosphere (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) carry out nitrogen fixation, converting nitrogen gas to nitrogenous compounds.[168] This serves to provide an easily absorbable form of nitrogen for many plants, which cannot fix nitrogen themselves. Many other bacteria are found as symbionts in humans and other organisms. For example, the presence of over 1,000 bacterial species in the normal human gut flora of the intestines can contribute to gut immunity, synthesise vitamins, such as folic acid, vitamin K and biotin, convert sugars to lactic acid (see Lactobacillus), as well as fermenting complex undigestible carbohydrates.[169][170][171] The presence of this gut flora also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion) and these beneficial bacteria are consequently sold as probiotic dietary supplements.[172]

text: Pathogens

text: If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy and tuberculosis. A pathogenic cause for a known medical disease may only be discovered many years after, as was the case with Helicobacter pylori and peptic ulcer disease. Bacterial diseases are also important in agriculture, with bacteria causing leaf spot, fire blight and wilts in plants, as well as Johne's disease, mastitis, salmonella and anthrax in farm animals.

text: Each species of pathogen has a characteristic spectrum of interactions with its human hosts. Some organisms, such as Staphylococcus or Streptococcus, can cause skin infections, pneumonia, meningitis and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vasodilation and death.[173] Yet these organisms are also part of the normal human flora and usually exist on the skin or in the nose without causing any disease at all. Other organisms invariably cause disease in humans, such as the Rickettsia, which are obligate intracellular parasites able to grow and reproduce only within the cells of other organisms. One species of Rickettsia causes typhus, while another causes Rocky Mountain spotted fever. Chlamydia, another phylum of obligate intracellular parasites, contains species that can cause pneumonia, or urinary tract infection and may be involved in coronary heart disease.[174] Finally, some species, such as Pseudomonas aeruginosa, Burkholderia cenocepacia, and Mycobacterium avium, are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis.[175][176]

text: Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria, or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. An example of how antibiotics produce selective toxicity are chloramphenicol and puromycin, which inhibit the bacterial ribosome, but not the structurally different eukaryotic ribosome.[177] Antibiotics are used both in treating human disease and in intensive farming to promote animal growth, where they may be contributing to the rapid development of antibiotic resistance in bacterial populations.[178] Infections can be prevented by antiseptic measures such as sterilising the skin prior to piercing it with the needle of a syringe, and by proper care of indwelling catheters. Surgical and dental instruments are also sterilised to prevent contamination by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection.

text: Significance in technology and industry

text: Bacteria, often lactic acid bacteria, such as Lactobacillus and Lactococcus, in combination with yeasts and moulds, have been used for thousands of years in the preparation of fermented foods, such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine and yogurt.[179][180]

text: The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills.[181] Fertiliser was added to some of the beaches in Prince William Sound in an attempt to promote the growth of these naturally occurring bacteria after the 1989 Exxon Valdez oil spill. These efforts were effective on beaches that were not too thickly covered in oil. Bacteria are also used for the bioremediation of industrial toxic wastes.[182] In the chemical industry, bacteria are most important in the production of enantiomerically pure chemicals for use as pharmaceuticals or agrichemicals.[183]

text: Bacteria can also be used in the place of pesticides in the biological pest control. This commonly involves Bacillus thuringiensis (also called BT), a gram-positive, soil dwelling bacterium. Subspecies of this bacteria are used as a Lepidopteran-specific insecticides under trade names such as Dipel and Thuricide.[184] Because of their specificity, these pesticides are regarded as environmentally friendly, with little or no effect on humans, wildlife, pollinators and most other beneficial insects.[185][186]

text: Because of their ability to quickly grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics and biochemistry. By making mutations in bacterial DNA and examining the resulting phenotypes, scientists can determine the function of genes, enzymes and metabolic pathways in bacteria, then apply this knowledge to more complex organisms.[187] This aim of understanding the biochemistry of a cell reaches its most complex expression in the synthesis of huge amounts of enzyme kinetic and gene expression data into mathematical models of entire organisms. This is achievable in some well-studied bacteria, with models of Escherichia coli metabolism now being produced and tested.[188][189] This understanding of bacterial metabolism and genetics allows the use of biotechnology to bioengineer bacteria for the production of therapeutic proteins, such as insulin, growth factors, or antibodies.[190][191]

text: Because of their importance for research in general, samples of bacterial strains are isolated and preserved in Biological Resource Centers. This ensures the availability of the strain to scientists worldwide.

text: History of bacteriology

text: Bacteria were first observed by the Dutch microscopist Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design.[192] He then published his observations in a series of letters to the Royal Society of London.[193][194][195] Bacteria were Leeuwenhoek's most remarkable microscopic discovery. They were just at the limit of what his simple lenses could make out and, in one of the most striking hiatuses in the history of science, no one else would see them again for over a century.[196] His observations had also included protozoans which he called animalcules, and his findings were looked at again in the light of the more recent findings of cell theory.

text: Christian Gottfried Ehrenberg introduced the word "bacterium" in 1828.[197] In fact, his Bacterium was a genus that contained non-spore-forming rod-shaped bacteria,[198] as opposed to Bacillus, a genus of spore-forming rod-shaped bacteria defined by Ehrenberg in 1835.[199]

text: Louis Pasteur demonstrated in 1859 that the growth of microorganisms causes the fermentation process, and that this growth is not due to spontaneous generation. (Yeasts and moulds, commonly associated with fermentation, are not bacteria, but rather fungi.) Along with his contemporary Robert Koch, Pasteur was an early advocate of the germ theory of disease.[200]

text: Robert Koch, a pioneer in medical microbiology, worked on cholera, anthrax and tuberculosis. In his research into tuberculosis Koch finally proved the germ theory, for which he received a Nobel Prize in 1905.[201] In Koch's postulates, he set out criteria to test if an organism is the cause of a disease, and these postulates are still used today.[202]

text: Ferdinand Cohn is said to be a founder of bacteriology, studying bacteria from 1870. Cohn was the first to classify bacteria based on their morphology.[203][204]

text: Though it was known in the nineteenth century that bacteria are the cause of many diseases, no effective antibacterial treatments were available.[205] In 1910, Paul Ehrlich developed the first antibiotic, by changing dyes that selectively stained Treponema pallidum—the spirochaete that causes syphilis—into compounds that selectively killed the pathogen.[206] Ehrlich had been awarded a 1908 Nobel Prize for his work on immunology, and pioneered the use of stains to detect and identify bacteria, with his work being the basis of the Gram stain and the Ziehl–Neelsen stain.[207]

text: A major step forward in the study of bacteria came in 1977 when Carl Woese recognised that archaea have a separate line of evolutionary descent from bacteria.[2] This new phylogenetic taxonomy depended on the sequencing of 16S ribosomal RNA, and divided prokaryotes into two evolutionary domains, as part of the three-domain system.[1]


document_title: Designated Survivor (season 1)

question_text: how many episodes in season 1 designated survivor

text: Designated Survivor (season 1)

text: Overview[edit]

text: On the night of the State of the Union, an explosion claims the lives of the President and everyone in the line of succession except for Secretary of Housing and Urban Development Thomas Kirkman, who had been named the designated survivor. Kirkman is immediately sworn in as President, unaware that the attack is just the beginning of what is to come.

text: Cast and characters[edit]

text: Main[edit]

text:
Kiefer Sutherland as President Thomas "Tom" Kirkman
Natascha McElhone as First Lady Alexandra "Alex" Kirkman
Adan Canto as Aaron Shore
Italia Ricci as White House Chief of Staff Emily Rhodes
LaMonica Garrett as Mike Ritter
Tanner Buchanan as Leo Kirkman (episodes 1-13; recurring episodes 14-21)
Kal Penn as White House Press Secretary Seth Wright
Maggie Q as Hannah Wells

tag: ul

text: Recurring[edit]

text:
Mckenna Grace as Penny Kirkman, Tom's daughter and Leo's younger sister.[6]
Peter Outerbridge as Charles Langdon, the former Chief of Staff and one of the survivors of the Capitol bombing who provides Wells with information about the conspiracy.
Malik Yoba as Jason Atwood, the Deputy Director of the FBI who initially spars with Wells over her investigation into the bombing but quickly becomes one of her most trusted allies.[7]
Kevin McNally as General Harris Cochrane, the Chairman of the Joint Chiefs of Staff who refuses to accept Tom as the new Commander in Chief and attempts to take matters into his own hands.[8]
Virginia Madsen as Congresswoman Kimble Hookstraten, a Republican from Missouri and the designated survivor for the Republican Party who supports Tom's authority while secretly harboring her own agenda.
Ashley Zukerman as Congressman Peter MacLeish, a third-term representative from Oregon who becomes a national hero following the bombing but struggles to hide a dark secret.[9]
George Tchortov as Nestor Lozano, a former CIA agent and wanted mercenary operating under the name "Catalan" who is heavily involved in the conspiracy.
Reed Diamond as John Forstell, the current Assistant Director of the FBI's Office of Professional Responsibility and the acting Attorney General who occasionally assists Wells in her investigation.
Mykelti Williamson as Admiral Chernow, the Vice Chairman of the Joint Chiefs of Staff who quickly becomes one of Tom's most trusted advisors.[10]
Michael Gaston as James Royce, the Governor of Michigan who openly defies the Kirkman administration and tries to establish his own supreme authority.[11]
Mariana Klaveno as Brooke Mathison, a clandestine operator in league with the people behind the Capitol bombing.
Jake Epstein as Chuck Russink, an FBI analyst who occasionally assists Wells in her investigation.
Lara Jean Chorostecki as Beth MacLeish, Peter MacLeish's wife and a member of the conspiracy who goads him into following through with their agenda.
Rob Morrow as Abe Leonard, a disgraced investigative journalist determined to expose the Kirkman administration's secrets.[12]
Geoff Pierson as Cornelius Moss, a former President of the United States whom Tom appoints as his Secretary of State.[13]
Mark Deklin as Senator Jack Bowman, a Republican from Montana who seeks to raise his national profile by opposing Tom's legislative agenda.
Kearran Giovanni as Senator Diane Hunter, a Democrat from Massachusetts and the Senate Minority Leader who has a habit of sparring with Bowman.
Terry Serpico as Patrick Lloyd, the CEO of a defunct private military firm and the mastermind behind the conspiracy.
Richard Waugh as Jay Whitaker, the Homeland Security Advisor and a member of the conspiracy.

text: Episodes[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
U.S. viewers
(millions)

1
1
"Pilot"
Paul McGuigan
David Guggenheim
September 21, 2016 (2016-09-21)
10.04[14]

When a sudden explosion destroys the Capitol Building during the State of the Union address, Secretary of Housing and Urban Development Tom Kirkman is sworn in as President after his predecessor and his fellow Cabinet members are pronounced dead. As he juggles adjusting to his new role and proving he is capable of leading the country, FBI agent Hannah Wells begins to suspect that the attack may be the first of many.

2
2
"The First Day"
Brad Turner
Story by : Jon Harmon Feldman
Teleplay by : David Guggenheim
September 28, 2016 (2016-09-28)
7.97[15]

Kirkman deals with his first challenges as Commander in Chief when civil rights abuses in Michigan reach a fever pitch and the designated survivor for the Republican Party comes forward; Wells suspects the FBI is being pointed in the wrong direction; a member of Congress who survived the bombing makes his presence known.

3
3
"The Confession"
Sergio Mimica-Gezzan
Jennifer Johnson & Paul Redford
October 5, 2016 (2016-10-05)
7.05[16]

Kirkman faces crisis after crisis as he juggles dealing with an interview that leaves many questioning the legitimacy of his Presidency and the fallout from a leaked video; Wells questions Congressman Peter MacLeish, the bombing's sole survivor, only to realize he isn't telling her the whole truth; Alex deals with a personal crisis when she discovers a bag of pills in Leo's bedroom drawer.

4
4
"The Enemy"
Paul Edwards
Dana Ledoux Miller & Jon Harmon Feldman
October 12, 2016 (2016-10-12)
7.00[17]

Kirkman juggles continuing to deal with the issue of civil rights in Michigan and finding a terrorist believed to be responsible for the bombing; Hannah suspects MacLeish isn't telling the truth about what happened on the night of the bombing; Alex seeks help from an unlikely ally; Seth takes on an unexpected new job.

5
5
"The Mission"
Paul Edwards
Sang Kyu Kim & Michael Russell Gunn
October 26, 2016 (2016-10-26)
5.96[18]

Kirkman dispatches a team of Navy SEALs to Algeria after learning that the government helped Majid Nassar, one of the terrorists claiming responsbility for the Capitol bombing, elude custody; Wells learns the truth about MacLeish's movements on the night of the bombing; Alex finds out someone from her past has made a damning allegation.

6
6
"The Interrogation"
Michael Katleman
Barbie Kligman & Jenna Richman
November 9, 2016 (2016-11-09)
5.56[19]

Kirkman's plans to elect a new Congress is put in jeopardy after a shooting disrupts a critical Governors' Summit; Wells and Atwood interrogate Majid Nassar about his purported role in the Capitol bombing; Aaron and Emily offer MacLeish the position of Vice President.

7
7
"The Traitor"
Frederick E. O. Toye
Jennifer Johnson & Michael Russell Gunn
November 16, 2016 (2016-11-16)
5.52[20]

Kirkman attempts to negotiate a three-way spy trade with Saudi Arabia and Russia; Alex finds herself face-to-face with the man who claims to be Leo's biological father; Wells pursues a lead from the Majid Nassar interrogation only to uncover a shocking secret.

8
8
"The Results"
Chris Grismer
Paul Redford & Sang Kyu Kim
November 30, 2016 (2016-11-30)
5.45[21]

Kirkman is forced to consider canceling the Congressional elections following a bioterrorism threat in Kansas City; Leo confronts his parents about the scandal revolving around his parentage; Wells' investigation into Majid Nassar's death takes a devastating turn.

9
9
"The Blueprint"
Richard J. Lewis
Dana Ledoux Miller & Michael Russell Gunn
December 7, 2016 (2016-12-07)
5.18[22]

Kirkman suspects a disgruntled NSA employee responsible for stealing classified information has an ulterior motive and Wells continues to search for information about MacLeish's military past as the number of people she can trust continues to dwindle.

10
10
"The Oath"
Frederick E. O. Toye
David Guggenheim
December 14, 2016 (2016-12-14)
6.18[23]

Kirkman and Emily attempt to confirm suspicions of a traitor in the White House; Wells juggles evading federal authorities and learning the identity of her mystery asset; MacLeish prepares to be sworn in as Vice President.

11
11
"Warriors"
Stephen Surjik
Paul Redford & Carol Flint
March 8, 2017 (2017-03-08)
5.86[24]

Kirkman is taken into surgery after being shot during MacLeish's swearing-in; Wells is interrogated about the information she has on MacLeish; Emily continues to avoid Aaron in the wake of a devastating revelation; MacLeish uses his hours as acting President to conceal his involvement in the failed assassination attempt.

12
12
"The End of the Beginning"
Mike Listo
David Guggenheim
March 15, 2017 (2017-03-15)
5.74[25]

Kirkman and Wells start working together to learn more about MacLeish's involvement in the Capitol bombing; Emily's strained relationship with Aaron is further tested; Alex grows suspicious as Kirkman begins to tighten his inner circle.

13
13
"Backfire"
Tara Nicole Weyr
Sang Kyu Kim & Pierluigi Cothran
March 22, 2017 (2017-03-22)
5.21[26]

Kirkman deals with the fallout from MacLeish's death; Wells unearths information about how MacLeish became involved in the conspiracy; Seth clashes with a reporter bent on exposing the administration's secrets; Alex reaches a difficult decision regarding her family's safety.

14
14
"Commander-in-Chief"
Frederick E. O. Toye
Michael Russel Gunn
March 29, 2017 (2017-03-29)
5.15[27]

Kirkman juggles preventing a genocide in an African nation and working with former President Cornelius Moss to organize his Cabinet; Wells interrogates former Chief of Staff Charles Langdon about his involvement in the conspiracy; Aaron makes a decision about his future in the White House.

15
15
"One Hundred Days"
Kenneth Fink
Dana Ledoux Miller
April 5, 2017 (2017-04-05)
5.19[28]

Kirkman announces his intention to officially initiate his first hundred days; Alex makes a statement that threatens to jeopardize the administration's agenda; Wells and Atwood set out to find the mysterious woman responsible for his son's murder; Hookstraten presents Aaron with an enticing offer.

16
16
"Party Lines"
Mike Listo
Jenna Richman
April 12, 2017 (2017-04-12)
4.82[29]

Kirkman's administration struggles to assemble a bipartisan coalition in order to pass a controversial gun control bill and Wells and Atwood uncover further evidence that suggests the conspirators are planning more attacks.

17
17
"The Ninth Seat"
Frederick E. O. Toye
Paul Redford
April 19, 2017 (2017-04-19)
5.06[30]

Kirkman is forced to improvise when Republican Senator Jack Bowman blocks one of his Supreme Court nominees; Wells and Atwood investigate a lead only to make a shocking revelation; Seth learns that Leonard is writing a story about the truth behind the Capitol bombing.

18
18
"Lazarus"
Chris Grismer
Jennifer Johnson
April 26, 2017 (2017-04-26)
5.11[31]

Kirkman's plan to nominate Hookstraten as Vice President is threatened when one of Hookstraten's old rivals begins a smear campaign; Wells' investigation puts her life in danger; Leonard receives inside information about the truth behind the bombing.

19
19
"Misalliance"
Norberto Barba
Dana Ledoux Miller & Jenna Richman
May 3, 2017 (2017-05-03)
4.62[32]

Kirkman juggles preparing for his first NATO summit and helping Hookstraten fight for her political future; Atwood secretly collects intelligence on a high-ranking member of the conspiracy; Wells finds herself forced to play a dangerous cat-and-mouse game.

20
20
"Bombshell"
Sharat Raju
Sang Kyu Kim
May 10, 2017 (2017-05-10)
4.92[33]

Kirkman's first NATO summit is thrown into chaos when Abe Leonard publishes a story with damning allegations; Wells tries to stay one step ahead of her kidnappers; the Secret Service makes another attempt to locate the traitor within the White House.

21
21
"Brace for Impact"
Frederick E. O. Toye
David Guggenheim
May 17, 2017 (2017-05-17)
5.07[34]

Kirkman authorizes a national manhunt for the mastermind behind the Capitol bombing; Wells sets out to prevent the conspirators from orchestrating another attack; a series of dangerous events culminates in a discovery no one saw coming.

text: Production[edit]

text: Development[edit]

text: Designated Survivor was ordered straight to series by ABC in December 2015,[1] with a formal announcement of 13 episodes in May 2016.[2][35] A month later, ABC revealed that the series would premiere on September 21, 2016.[36] Eight days after the premiere, on September 29, 2016, ABC gave the series a full season order.[4]

text: Created by David Guggenheim, the series is executive produced by Simon Kinberg, Sutherland, Suzan Bymel, Aditya Sood, and Nick Pepper. Paul McGuigan directed the pilot episode. Amy B. Harris was set to be the showrunner in February 2016, but after the series' official pick-up in May, it was announced she would be stepping down due to creative differences, and that Jon Harmon Feldman was in talks to replace her.[37] In July 2016, Feldman was confirmed as showrunner/executive producer.[7] In December 2016, Jeff Melvoin was hired as showrunner, replacing the departing Feldman.[38] Kal Penn, formerly associate director in the White House's Office of Public Engagement, serves as a consultant for the series as well as acting in the main cast.[39]

text: Writing[edit]

text: Producers Jon Harmon Feldman and Guggenheim described the series as more than one genre, drawing inspiration from other thriller-dramas, with Guggenheim explaining, "There is a West Wing component of a man governing and his team governing our nation at this critical time. It's also the Homeland aspect of investigating the conspiracy. It also has a House of Cards component, which is the characters and the business of government through the eyes of these characters."[40][41]

text: Casting[edit]

text: Kiefer Sutherland joined the cast in December 2015, playing Tom Kirkman, the Secretary of Housing and Urban Development who suddenly becomes President.[42] Sutherland had previously no intention of doing television again, but changed his mind after reading the first script of the series, saying, "I remember getting to the end of the script and thinking I was potentially holding the next 10 years of my life in my hands."[41]

text: In February 2016, it was announced that Kal Penn, Maggie Q, Natascha McElhone, and Italia Ricci had been cast as Kirkman's speech writer; Hannah, the lead FBI agent on the bombing of the Capitol; Kirkman's wife, an EEOC attorney; and Emily, Kirkman's Chief of Staff, respectively.[43] Shortly after, Adan Canto had joined the series as Aaron Shore, the White House Deputy Chief of Staff.[44] In early March, LaMonica Garrett joined the cast as Mike Ritter, Kirkman's Secret Service agent,[45] and Tanner Buchanan and Mckenna Grace had been cast as Kirkman's children.[6]

text: In July 2016, Malik Yoba was announced for a recurring role as Jason Atwood, the seasoned Deputy Director of the FBI, to appear in seven episodes,[7] while Virginia Madsen had been cast in the recurring role of Kimble Hookstraten, a conservative Congresswoman and the designated survivor for the rival political party.[46] A month later, Ashley Zukerman joined the series in a recurring role as Peter MacLeish, an Afghan War veteran and popular third-term Congressman.[9] In September 2016, Mykelti Williamson was cast as Admiral Chernow, a career military man and the Chairman of the Joint Chiefs of Staff.[10] On November 4, 2016, it was announced that Mariana Klaveno had been cast for the show as the Dark-Haired Woman, a clandestine operator in league with the people behind the Capitol attack.[47]

text: Reception[edit]

text: Critical response[edit]

text: Review aggregator website Rotten Tomatoes gave the first season an approval rating of 85% based on 52 reviews, with an average rating of 6.98/10. The site's critical consensus reads, "Kiefer Sutherland skillfully delivers the drama in Designated Survivor, a fast-paced, quickly engrossing escapist political action fantasy."[48] Metacritic reported a score of 71 out of 100 based on 35 reviews, indicating "generally favorable reviews".[49]

text: Terri Schwartz from IGN gave the first episode a rating of 8.0/10, saying, "Designated Survivor is a strong debut for a show that will fit well alongside Quantico and Scandal in ABC's government-set political drama lineup."[50] Variety said that the episode "does everything it needs to, checking off the necessary boxes for the unwilling American hero-president in efficient, compelling scenes."[51] Chuck Barney from Mercury News called the first episode "suspenseful".[52] Writing for TV Insider, Matt Roush compared Designated Survivor with other series as he said "fall's niftiest new drama has West Wing idealism, Homeland suspense and House of Cards political intrigue in its robust and compelling DNA."[53] Zack Handlen from The A.V. Club wrote positively about the show and the premiere, praising Sutherland's performance and commented on the symbol of Sutherland's glasses as he said, "The glasses he's wearing serve as a way to tell us this is a different kind of hero, but they're also a form of camouflage, making it easier for us to understand why so many people would underestimate this man."[54]

text: The editors of TV Guide placed Designated Survivor first among the top ten picks for the most anticipated new shows of the 2016–17 season. In writer Alexander Zalben's overall review, he pointed out the keys to one of the strongest pilots he had seen so far: "Designated Survivor is the rare show that delivers on the hype, and surpasses it," and later stating "It's shocking that a show can balance all of these elements, but credit a magnetic cast that hits the ground running, a crack script that makes the first hour feel like 10 minutes and, of course, Sutherland as the anchor that keeps it all grounded." Zalben's review concluded with this recommendation: "There's a reason Designated Survivor wasn't just the top pick across all of our Editors' lists, but also on the list compiled from TVGuide.com viewers' Watchlist adds: this is a show that delivers on its premise, feels timely, and most importantly, is a ton of fun."[55]

text: On the other hand, after watching the first episode of the first season, The Guardian's Brian Moylan criticized the dialogue, writing in his review that "this drama needs dialogue that won’t make the citizenry’s eyeballs roll", adding that the show features "meaningless platitudes" of a "we’re going to do this my way" attitude, and concluded by writing, "All we’re left with is a really great concept without the backing of a real leader behind it." Moylan also wrote that "there’s not enough family tension for it to be a domestic drama, not enough government intrigue to make it a political show, and not enough investigation to make it a procedural."[56] TVLine's Dave Nemetz drew references between Kirkman and Jack Bauer, Kiefer Sutherland's role in drama thriller 24, writing that "Sutherland does a good job portraying Kirkman’s deep ambivalence about the situation he’s been handed. But when he has to play hardball with an Iranian ambassador, the tough talk comes too easily to him. It’s like Kirkman has been possessed by the ghost of Jack Bauer". Nemetz also questioned the series' longevity; "As compelling as Designated Survivor's concept is, it’s hard to see how it will sustain itself as a weekly series".[57]

text: Ratings[edit]

text: The first episode set a record for DVR viewers with 7.67 million, surpassing the September 25, 2014, record of almost 7 million set by the pilot of How to Get Away with Murder.[58][59]

text:
No.
Title
Air date
Rating/share
(18–49)
Viewers
(millions)
DVR
(18–49)
DVR viewers
(millions)
Total
(18–49)
Total viewers
(millions)

1
"Pilot"
September 21, 2016
2.2/8
10.04[14]
2.2
7.67
4.4
17.71[58]

2
"The First Day"
September 28, 2016
1.8/6
7.97[15]
2.1
7.65
3.9
15.62[60]

3
"The Confession"
October 5, 2016
1.6/6
7.05[16]
1.9
7.32
3.5
14.33[61]

4
"The Enemy"
October 12, 2016
1.6/6
7.00[17]
1.9
6.89
3.5
13.89[62]

5
"The Mission"
October 26, 2016
1.2/5
5.96[18]
2.0
7.07
3.2
13.03[63]

6
"The Interrogation"
November 9, 2016
1.2/4
5.56[19]
1.8
6.36
3.0
11.92[64]

7
"The Traitor"
November 16, 2016
1.2/4
5.52[20]
1.7
6.40
2.9
11.92[65]

8
"The Results"
November 30, 2016
1.3/4
5.45[21]
1.7
6.50
3.0
11.95[66]

9
"The Blueprint"
December 7, 2016
1.1/4
5.18[22]
1.7
6.69
2.8
11.88[67]

10
"The Oath"
December 14, 2016
1.2/4
6.17[23]
1.7
6.19
2.9
12.36[68]

11
"Warriors"
March 8, 2017
1.3/5
5.86[24]
1.5
5.80
2.8
11.69[69]

12
"The End of the Beginning"
March 15, 2017
1.3/5
5.74[25]
1.4
5.53
2.7
11.27[70]

13
"Backfire"
March 22, 2017
1.1/4
5.21[26]
1.4
5.66
2.5
10.87[71]

14
"Commander-in-Chief"
March 29, 2017
1.1/4
5.15[27]
1.5
5.79
2.6
10.94[72]

15
"One Hundred Days"
April 5, 2017
1.1/4
5.19[28]
1.5
5.68
2.6
10.87[73]

16
"Party Lines"
April 12, 2017
0.9/3
4.82[29]
1.4
5.43
2.3
10.31[74]

17
"The Ninth Seat"
April 19, 2017
1.0/4
5.06[30]
1.4
5.50
2.4
10.56[75]

18
"Lazarus"
April 26, 2017
1.1/4
5.11[31]
N/A
N/A
N/A
N/A

19
"Misalliance"
May 3, 2017
0.9/4
4.62[32]
1.4
5.42
2.3
10.04[76]

20
"Bombshell"
May 10, 2017
1.0/4
4.92[33]
1.2
5.23
2.2
10.15[77]

21
"Brace for Impact"
May 17, 2017
1.1/4
5.07[34]
1.2
5.30
2.3
10.37[78]


document_title: Pikes Peak International Hill Climb

question_text: who won the pikes peak hill climb this year

text: Pikes Peak International Hill Climb

text: History[edit]

text: Early history[edit]

text: The first Pikes Peak Hill Climb was promoted by Spencer Penrose, who had converted the narrow carriage road into the much wider Pikes Peak Highway.[4]

text: The first Penrose Trophy was awarded in 1916 to Rea Lentz with a time of 20:55.60.[4][5][6] In the same year Floyd Clymer won the motorcycle class with a time of 21:58.41.[7] In 1924 the final Penrose Trophy was awarded to Otto Loesche in his Lexington Special.[8] In the years following, Glen Scultz and Louis Unser shared a rivalry and won the event 12 times between them.[5] In 1929 the popular stock car class was added to the event.[4][6]

text: Following world war two, Louis Unser returned to his winning ways at Pikes Peak, winning a further three more times between 1946 and 1970, these wins were tightly contended with rival Al Rogers.[4][5] During this time the event was part of the AAA and USAC IndyCar championship.[9] In 1953, the SCCA sponsors the event, bringing with it an influx of sports cars. In this period the course record was broken every year from 1953 until 1962, this is the largest string of record breaking runs in the event's history. The majority of these records were set by Bobby Unser, the younger brother of Louis.[5] In 1954 motorcycles return to the event, the first time since its inception 1916.[6] The motorcycle overall victory that year went to Bill Meier riding a Harley-Davidson.[7]

text: In 1971 the event was won by the first non-gasoline vehicle (propane), this was also the first overall victory from the stock car class (1970 Ford Mustang), the car was driven by the Danish-American Ak Miller.[6]

text: European involvement[edit]

text: In 1984 the first European racers took part in the PPIHC with Norwegian Rallycrosser Martin Schanche (Ford Escort Mk3 4x4) and French Rally driver Michèle Mouton (Audi Sport quattro), thereby starting a new era for European teams in the almost unknown American hillclimb.[10] While Schanche failed to set a new track record, due to a flat right front tire, Mouton (together with her World Rally Championship co-driver Fabrizia Pons from Italy) won the Open Rally category, but failed to win the event overall. Mouton achieved the overall victory and course record in the following year.[10][7]

text: In 1989, an award-winning short film about the 1988 event was released by French director Jean-Louis Mourey. The film, titled Climb Dance, captured the efforts of Finnish former World Rally Champion Ari Vatanen, as he won the event in a record-breaking time with his turbocharged Peugeot 405 Turbo-16.[5][7][11]

text: Paving of the highway[edit]

text: The City of Colorado Springs began to pave the highway in 2002 after losing a lawsuit against the Sierra Club, which sued on account of erosion damage to streams, reservoirs, vegetation and wetlands downstream from the 1.5 million tons of road gravel deposited over several decades.[12][13] The local authority paved approximately 10% of the route each year after the order. The 2011 event was the last race with dirt sections, comprising approximately 25% of the course.[3]

text: During this evolutionary period of the event, the Japanese driver Nobuhiro Tajima with Suzuki cars scored 6 overall victories (2006 - 2011) and two course records.[4][10] His 2011 record was the first to break the 10 minute barrier.[5]

text: Hill Climb champion Rod Millen warned at the time that paving the road would put an end to the race.[14] However, the 2012 race saw over 170 racer registrations by December 2011, compared with 46 at the same time the previous year.[15]

text: The 90th running of the event happened in 2012 and saw a larger field and a longer race day than ever before. This was the first time the race has been run on all asphalt leading to the breaking of several records, notably the overall record, which fell numerous times during the event finally falling to Rhys Millen the son of previous event winner Rod Millen, in the Time Attack Division. During the event Mike Ryan spun his big rig in a hairpin in a section called the "W"s, hitting the guard rail, he then managed to execute a three-point turn and continued on course, at which point he broke his old record by 5 seconds. This highlighted the change that a fully paved course made to the speed of the event.[16] The 2012 event also saw the first motorcycle to achieve a sub 10 minute time with Carlin Dunne in the 1205 Division riding a Ducati with a time of 9:52.819 which was only 1.5 seconds slower than the previous year's overall record.

text: 2013 saw the nine-minute barrier shattered by WRC legend Sébastien Loeb, with a time of 8:13.878, while Rhys Millen ended up second with 9:02.192, beating his own record by more than 44 seconds.[17] Jean-Philippe Dayrault finished third with a time of 9:42.740, and Paul Dallenbach fourth with a time of 9:46.001, making it four drivers to beat the overall record set only the previous year.

text: Emergence of electric vehicles[edit]

text: Electric cars have featured on and off in the PPIHC since the early 1980s. In 1981 Joe Ball took a Sears Electric Car to the top in 32:07:410, in 1994 Katy Endicott brought her Honda to the top in 15:44.710 and in 2013 Nobuhiro Tajima broke the 10 minute barrier with a time of 9:46.530 in his E-RUNNER Pikes Peak Special. In the following years electric entries would become more common, steadily breaking their powertrain records and eventually the overall record in 2018.[5][7][18]

text: For hill-climb events and this event in particular it is reasonable to suggest that a modern, well designed electric car will be at an advantage over internal combustion engined cars. The issue of limited range does not apply to short sprints and the twisty nature of the Pikes Peak course lends itself well to the almost instant torque delivery of electric motors. In addition to this, the lowering air density of high altitudes does not reduce the power available to the driver as it does with air breathing engines.[19][20]

text:
Although the 2014 event was won by a gasoline powered car; second (Greg Tracy), third (Hiroshi Masuoka) and fourth (Nobuhiro Tajima) places overall were taken by electric cars.[21]
In 2015, electric cars placed first (Rhys Millen) and second (Nobuhiro Tajima) overall.[22][23] In an interview with Rhys Millen, he said that he had lost power to the car's rear motor pack before the halfway point. Had this not happened he had expected his run to be 30 seconds faster.[24]
In 2016 gasoline again took top honours but electric completed the podium taking second (Rhys Millen) and third (Tetsuya Yamano) as well as fifth (Nobuhiro Tajima) places overall.[25]

text: At the 2018 event, an electric car set a new overall record for the first time in the event's history. Frenchman Romain Dumas completed the course in the all-electric Volkswagen I.D. R with a time of 7:57.148.[19][26]

text: Current racing divisions & classes[edit]

text:
The Pikes Peak International Hill climb consists of seven divisions incorporating twelve classes for both cars and motorcycles.
[27]
An additional four special record classes consisting of former classes are defined in the appendix.
[1]

text: Car divisions & classes[edit]

text: Unlimited Division

text: Anything goes in the Unlimited Division as long as it passes safety inspection and meets the PPIHC’s general rules. The Unlimited Division features the most exotic vehicles, most of them built specifically for this race. These race cars have the best chance of setting a new overall race record. In 2018, Romain Dumas set a new record of 7'57"148 in the all-electric Volkswagen I.D. R Pikes Peak, beating Sébastien Loeb's previous record by over 15 seconds.[28]

text: Time Attack Division

text: A division for production based two and four wheel drive vehicles. Only closed cockpit four-wheeled vehicles are allowed to participate.

text: This class features highly modified and specialised production based race vehicles.

text: Making its debut on Pikes Peak this year is the first official one-make Porsche category, exclusive to the Porsche Cayman GT4 Clubsport in four variants: Clubsport, Clubsport Trophy Specification, Clubsport MR, and Clubsport 2017 IMSA GS.

text: Pikes Peak Challenge Car Division

text: Established in 2014, the Pikes Peak Challenge Division encompasses a wide variety of class options.

text: The traditional Pikes Peak single-seater race cars with designs ranging from Indy style sprinters to dune buggies. Open wheel cars have competed in every event since the inaugural race in 1916.

text: Production based vehicles unlimited permitted modifications.

text: In keeping with the mission statement of the Pikes Peak International Hill Climb, specifically to "demonstrate advancements in the practical application of motor sports technology", the race encourages competitors with vehicles that do not meet the technical specifications of PPIHC sanctioned divisions and classes to enter in the Exhibition Class. While there are no class records for this class because of its exhibition status, entries are eligible for recording an overall course record.

text: Motorcycle divisions & classes[edit]

text: Pikes Peak Heavyweight Division

text: This is the top motorcycle division offered at Pikes Peak. It was formerly known as the Pikes Peak Open Motorcycle class. Competitors are eligible to enter vehicles powered by two or four-stroke engines of no more than 4 cylinders which displace between 851 and 1305cc.

text: Pikes Peak Middleweight Division

text: Competitors are eligible to enter vehicles powered by two or four-stroke engines of no more than 4 cylinders which displace between 501 and 850cc.

text: Pikes Peak Lightweight Division

text: Competitors are eligible to enter vehicles powered by two or four-stroke engines of no more than 2 cylinders which displace no more than 500cc.

text: Established is 2014, the Pikes Peak Challenge Motorcycle Division encompasses a wide variety of class options.

text: Intended to allow manufacturers to exhibit and trial their electric bike technology.

text: Essentially four-wheeled motorcycles, these machines have very few limitations. Engines must be commercially available and either be a 450-750cc single cylinder 4-stroke or a 250-550cc 1 or 2 cylinder 2-stroke.

text: This division includes Utility Terrain Vehicles and other vehicles that don’t fit in other Pikes Peak Divisions. While there are no records for this class because of its exhibition status entries are eligible for recording an overall course or 2-wheeled record.

text: Records from the Appendix of the Regulations[edit]

text: Time Attack 2 Production Record

text: This class features production based two- or four-wheeled vehicles with minimal modification allowed. All cars entered must have a valid manufacturer issued VIN and a minimum production run of 500.

text: Vintage Car Record

text: A class open to cars manufactured in 1995 or earlier, eligible vehicles must have competed in a past event.

text: Sidecar Record

text: Motorcycle and sidecar, consisting of three wheels. The vehicle is quite unrestricted however forced induction is not permitted and the vehicle must be able to safely and comfortably carry a passenger. If a sidecar entry is also entered in the Exhibition Powersport class then a passenger is only permitted to ride during official practise sessions.

text: Vintage Motorcycle Record

text: A class open to vintage motorcycles.

text: Race Records[edit]

text: Below follows all currently recognised records. Records set during the most recent running of the event are in bold type.

text: Division & Class Records[edit]

text:
Current 4-Wheel Records[29]

Division

Class

Year

Name

Vehicle

Time

Unlimited
2018
Romain Dumas
Volkswagen I.D. R[note 1]
7:57.148

Time Attack
Time Attack 1
2018
David Donohue
2017 Porsche GT3 R
9:37.152

Pikes Peak Challenge Car
Open Wheel
2017
Clint Vahsholtz
2013 Ford Open
9:35:747

Pikes Peak Open
2018
Peter Cunningham
2018 Acura TLX GT
9:27.352

Porsche Cayman GT4 Clubsport
2018
Travis Pastrana
2016 Porsche Cayman GT4 Clubsport
10:33.897

text:
Current 2-Wheel Records[29]

Division

Class

Year

Name

Vehicle

Time

Pikes Peak Heavyweight
2017
Chris Fillmore [note 2]
2017 KTM Super Duke 1290 R
9:49:625

Pikes Peak Middleweight
2018
Chris Fillmore
2018 KTM 790 Duke
10:04:038

Pikes Peak Lightweight
2017
Davey Durelle
2009 Aprilia SXV450
10:35.354

Pikes Peak Challenge Motorcycle
Electric
2013
Carlin Dunne
2013 Lightning Electric Superbike
10:00.694

Quad
2016
Cyril Combes [note 2]
2011 Suzuki KTM JF Prototype
11:05.664

text: Non-Division & Class Records[edit]

text:
Records from the Appendix of the PPIHC Rule Book[1][29]

Type

Year

Name

Vehicle

Time

Time Attack 2 (Production)
2015
David Donner
2014 Porsche 911 Turbo S
10:26.896

Vintage Car
2017
Spencer Steele
1995 PVA 2
10:25.989

Sidecar
2016
John Wood &  Matthew Blank
1999 Shelbourne Superlite F2
11:26.644

Vintage Motorcycle
2012
Marc LaNoue
1969 Triumph Bonnie
12:39.782

text:
Alternative Fuel Records[29]

Fuel

Division/Class

Year

Name

Vehicle

Time

Electric
Modified
2018
Romain Dumas
Volkswagen I.D. R
7:57.148

Production
2016
Blake Fuller
2016 Tesla S P90D
11:48.264

Diesel
Exhibition
2015
Uwe Nittel
2016 Mercedes Benz C300 d 4 MATIC
11:37.149

Natural Gas
Open Wheel
1993
Johnnie Rogers
Wells-Coyote
11:50.090

Propane
Exhibition/PPO
2012
Randy Schranz
2012 Shelby Cobra
11:11.218

Turbine
Open Rally
1981
Steve Bolan
Bolan-Allison
15:27.180

Hybrid
Time Attack 1
2018
James Robinson
2017 Acura NSX
10:02.448

text:
Drivetrain Records[29]

Drivetrain

Division/Class

Year

Name

Vehicle

Time

Front-Wheel Drive
Pikes Peak Open
2018
Nick Robinson
2018 Acura TLX A-Spec
10:48.094

Rear-Wheel Drive
Unlimited
2018
Simone Faggioli[note 2]
2018 Norma M20 SF PKP
8:37.230

All-Wheel Drive
Unlimited
2018
Romain Dumas
Volkswagen I.D. R[note 1]
7:57.148

text: Winners[edit]

text: The Pikes Peak International Hill Climb is an event run by both cars and motorcycles. The overall honours have always fallen to vehicles in car divisions, however motorcycles have their own divisions, records and winners. Cars have entered the event every year since its inception in 1916 (with the exception of years during the world wars) whereas motorcycles have only entered in a limited number of years.

text: Overall Winners[edit]

text: Overall winners can compete under any class of cars or motorcycles, although the majority come from the open wheel and more recently the unlimited classes. A time in italics indicates this was a previous course record, a time in bold indicates the current course record.

text:
Table of overall winners.[5]
show

Year
Winner
Vehicle
Time
Notes

1916

 Rea Lentz

Romano Special

20:55.600

1917-1919

No competition due to World War 1

1920

 Otto Loesche

Lexington Special

22:25.400

1921

 King Rhiley

Hudson Special

19:16.200

1922

 Noel Bullock

Ford Special

19:50.900

1923

 Glen Shultz

Hudson Essex

18:47.000

1924

 Otto Loesche

Lexington Special

18:15.000

1925

 Charles H. Myers

Chandler Special

17:48.400

1926

 Glen Shultz

Stutz

18:19.400

1927

 Glen Shultz

Stutz

18:25.100

1928

 Glen Shultz

Stutz Special

17:41.600

1929

 Edward Phillips

Shultz Stutz 8

18:22.800

1930

 Glen Shultz

Stutz DV-32

18:08.700

1931

 Charles H. Myers

Hunt Special

17:10.300

1932

 Glen Shultz

Shultz/Stutz Special

16:47.200

1933

 Glen Shultz

Stutz DV-32

17:27.500

1934

 Louis Unser

Stutz Special

16:01.800

1935

 W.P. Bentrup

1935 Chevrolet 1 1/2-ton Truck

26:12.000

[note 3]

1936

 Louis Unser

Shultz Stutz

16:28.100

1937

 Louis Unser

Stutz DV-32

16:27.300

1938

 Louis Unser

Loop Cafe Special

15:49.900

1939

 Louis Unser

Snowberger Special

15:39.400

1940

 Al Rogers

Joe Coniff Special

15:59.900

1941

 Louis Unser

Burd Special

15:35.200

1942-1945

No competition due to World War 2

1946

 Louis Unser

Maserati

15:28.700

[note 4]

1947

 Louis Unser

Maserati

16:34.770

[note 5]

1948

 Al Rogers

Coniff Special Offenhauser

15:51.300

[note 5]

1949

 Al Rogers

Coniff Special

15:54.260

[note 5]

1950

 Al Rogers

Coniff Special

15:39.000

[note 5]

1951

 Al Rogers

Offenhauser

15:39.700

[note 5]

1952

 George Hammond

Kurtis Kraft Offenhauser Special

15:30.650

[note 5]

1953

 Louis Unser

Federal Engineering Special

15:15.400

[note 5]

1954

 Keith Andrews

Joe Hunt

14:39.700

[note 5]

1955

 Bob Finney

Dick Frenzel Special

14:27.200

[note 5]

1956

 Bobby Unser

Unser Special

14:27.000

[note 6]

1957

 Bob Finney

Dick Frenzel Special

14:11.700

[note 6]

1958

 Bobby Unser

Unser Special

13:47.900

[note 6]

1959

 Bobby Unser

Unser Special

13:36.500

[note 6]

1960

 Bobby Unser

Unser Special

13:28.500

[note 6]

1961

 Bobby Unser

Unser Special

12:56.700

[note 6]

1962

 Bobby Unser

Unser Special

12:05.800

[note 6]

1963

 Bobby Unser

Chevrolet 327

12:30.600

[note 6]

1964

 Al Unser

Offenhauser

12:24.500

[note 6]

1965

 Al Unser

Harrison Ford

12:54.300

[note 7]

1966

 Bobby Unser

Chevrolet

12:23.800

[note 7]

1967

 Wes Vandervoort

Chevrolet

12:46.300

[note 7]

1968

 Bobby Unser

Rislone Special

11:54.900

[note 7]

1969

 Mario Andretti

Chevrolet STP Special

12:44.070

[note 7]

1970

 Ted Foltz

Chevrolet 303

12:41.100

[note 6]

1971

 Ak Miller

1970 Mustang

14:18.600

1972

 Roger Mears

Volkswagen 2180

13:26.840

1973

 Roger Mears

Volkswagen 2180

12:54.790

1974

 Errol Kobilan

Sprint Chevrolet 302

12:54.770

1975

 Orville Nance

Chevrolet 327

12:36.650

1976

 Rick Mears

Porsche 2386

12:11.890

1977

 Bob Herring

Chevrolet 350

12:15.720

1978
 Errol Kobilan
Chevrolet
11:55.830

1979
 Dick Dodge Jr.
Hoffpauir Wells Coyote Chevrolet
11:54.180

1980
 Ted Foltz
1970 Chevrolet 350
12:15.810

1981
 Gary Lee Kanawyer
1976 N-D Porsche
12:03.960

1982
 Bill Brister
Woziwodzki Wells Coyote Chevrolet
11:44.820

1983
 Al Unser, Jr.
Woziwodzki Wells Coyote Chevy
11:38.300

1984
 Bill Brister
1981 Wells Coyote
11:44.490

1985
 Michèle Mouton
Audi Sport Quattro S1
11:25.390

1986
 Bobby Unser
Audi Sport Quattro SL
11:09.220

1987
 Walter Röhrl
Audi Sport Quattro E2 Pikes Peak
10:47.850

1988
 Ari Vatanen
Peugeot 405 Turbo 16
10:47.220

1989
 Robby Unser
Peugeot 405 Turbo 16
10:48.340

1990
 Robby Unser
Unser Chevrolet
11:32.860

1991
 David Donner
Donner-Dykstra Chevrolet
11:12.420

1992
 Robby Unser
Unser Chevrolet
10:53.870

1993
 Paul Dallenbach
Davis Chevrolet
10:43.630

1994
 Rod Millen
Toyota Celica AWD Turbo
10:04.060

1995
 Nobuhiro Tajima
Suzuki Grand Vitara
7:53.000
[note 8]

1996
 Rod Millen
Toyota Celica
10:13.640

1997
 Rod Millen
Toyota Celica
10:04.540

1998
 Rod Millen
Toyota Celica
10:07.700

1999
 Rod Millen
Toyota Celica
10:11.150

2000
 Larry Ragland
2000 GMC Envoy
11:17.660

2001
 Gary Lee Kanawyer
1981 Wells Coyote
10:39.760

2002
 David Donner
1997 Donner Dykstra
10:52.300
[note 9]

2003
 Paul Dallenbach
2000 PVA-01
11:34.700
[note 10]

2004
 Robby Unser
Subaru Impreza STIE
11:47.280
[note 11]

2005
 David Donner
Donner/Dykstra Special
11:15.680
[note 12]

2006
 Nobuhiro Tajima
Suzuki Sport
7:38.900
[note 8] [note 13]

2007
 Nobuhiro Tajima
Suzuki XL7
10:01.408
[note 14]

2008
 Nobuhiro Tajima
Suzuki XL7
10:18.250
[note 15]

2009
 Nobuhiro Tajima
Suzuki SX4
10:15.368
[note 16]

2010
 Nobuhiro Tajima
Suzuki SX4
10:11.490
[note 17]

2011
 Nobuhiro Tajima
Suzuki SX4
9:51.278
[note 18]

2012
 Rhys Millen
Hyundai Genesis Coupe
9:46.164
[note 19]

2013
 Sébastien Loeb
Peugeot 208 T16 Pikes Peak
8:13.878

2014
 Romain Dumas
Norma M20 RD
9:05.801

2015
 Rhys Millen
eO PP03
9:07.222
[note 1]

2016
 Romain Dumas
Norma M20 RD
8:51.445

2017
 Romain Dumas
Norma M20 RD
9:05.672

2018
 Romain Dumas
Volkswagen I.D. R
7:57.148
[note 1]

text: Motorcycle Winners[edit]

text: Motorcycle winners can compete under any class, although the majority come from open or large displacement classes. A time in italics indicates this was a previous motorcycle record, a time in bold indicates the current motorcycle record.

text:
Table of motorcycle winners.[7]
show

Year
Winner
Vehicle
Time
Notes

1916
 Floyd Clymer
Excelsior
21:58.410

1917-1953

No motorcycle competition records

1954
 Bill Meier
Harley-Davidson
15:34.100

1955
 Don Tindall
Harley-Davidson
16:08.600

1956-1970

No motorcycle competition records

1971
 Gary Myers
Husqvarna
15:11.960

1972
 Steve Scott
Bultaco
15:13.470

1973
 Rick Deane
Triumph 750
13:56.030

1974
 Bob Conway
Yamaha 750
13:54.570

1975
 Rick Deane
Triumph 750
13:54.620

1976
 Rick Deane
Triumph 750
13:12.610

1977-1979

No motorcycle competition records

1980
 Lonnie Houtchens
Yamaha 750
13:44.730

1981
 Brian Anderson
Triumph 750
13:20.860

1982
 Arlo Englund
NA
13:19.280

1983-1990

No motorcycle competition records

1991
 Brian Anderson
Wood-Rotax 600
13:24.820

1992
 Brian Anderson
Wood-Rotax
12:54.000

1993
 Clint Vahsholtz
Wood-Rotax
12:29.380

1994
 Clint Vahsholtz
Wood-Rotax 600
12:21.130

1995
 Clint Vahsholtz
1992 Wood-Rotax
09:17.100
[note 8]

1996
 Davey Durelle
1988 Wood-Rotax
12:33.730

1997
 Davey Durelle
1988 Wood-Rotax
12:21.960

1998
 John Stallworth
1987 Yamaha Banshee 430
12:52.370

1999
 Lonnie Eubanks
Yamaha
12:42.190

2000
 Bobby Parr
LSR Lightweight
12:37.860

2001
 Bobby Parr
LSR
12:09.160

2002
 Bobby Parr
Lone Star
12:30.000
[note 9]

2003
 Bobby Parr
Lightweight
12:28.480
[note 10]

2004
 Davey Durelle
Honda CRF
12:27.810
[note 11]

2005
 Micky Dymond
KTM
12:12.614
[note 12]

2006
 Gary Trachy
Husqvarna SMR
11:46.841
[note 13]

2007
 Davey Durelle
2005 Rotax
11:41.756
[note 14]

2008
 Davey Durelle
Aprilia SM 550
11:42.991
[note 15]

2009
 Davey Durelle
Aprilia SXV
11:48.649
[note 16]

2010
 Gary Trachy
TM 660
11:33.700
[note 17]

2011
 Carlin Dunne
Ducati Multistrada 1200
11:11.329
[note 18]

2012
 Carlin Dunne
Ducati Multistrada
9:52.819
[note 19]

2013
 Carlin Dunne
2013 Lightning Electric Superbike
10:00.694

2014
 Jeremy Toye
2013 Kawasaki Ninja ZX-10R
09:58.687

2015
 Jeffrey Tigert
2014 Honda CBR1000RR
10:02.735

2016
 Bruno Langlois
2015 Kawasaki Z1000
10:13.106

2017
 Chris Fillmore
2017 KTM Super Duke 1290 R
9:49:625

2018
 Carlin Dunne
2018 Ducati MTS-1260 Pikes Peak
9:59.102


document_title: Lymph capillary

question_text: when do anchoring filaments open spaces between endothelial cells in lymph capillaries

text: Lymph capillary

text:
Lymphatic capillary
Diagram showing the formation of lymph from interstitial fluid (labeled here as "Tissue fluid"). Note: how the tissue fluid is entering the blind ends of lymph capillaries (indicated by deep green arrows)DetailsSystem
Lymphatic systemIdentifiersLatin
vas lymphocapillareTA
A12.0.00.044TH
H3.09.02.0.05004FMA
5028
Anatomical terminology[edit on Wikidata]

text: Lymph capillaries or lymphatic capillaries are tiny, thin-walled vessels located in the spaces between cells (except in the central nervous system and non-vascular tissues) which serve to drain and process extra-cellular fluid. Upon entering the lumen of a lymphatic capillary, the collected fluid and associated cells (notably white blood cells) is known as lymph. Each lymphatic capillary carries lymph into a lymphatic vessel, which in turn connects to a lymph node. Lymph is ultimately returned to the venous circulation.

text: Lymphatic capillaries are slightly larger in diameter than blood capillaries, and have closed ends (unlike the loop structure of blood capillaries). Their unique structure permits interstitial fluid to flow into them but not out. The ends of the endothelial cells that make up the wall of a lymphatic capillary overlap. When pressure is greater in the interstitial fluid than in lymph, the cells separate slightly, like the opening of a one-way swinging door, and interstitial fluid enters the lymphatic capillary. When pressure is greater inside the lymphatic capillary, the cells adhere more closely, and lymph cannot escape back into interstitial fluid.  Attached to the lymphatic capillaries are anchoring filaments, which contain elastic fibers. They extend out from the lymphatic capillary, attaching lymphatic endothelial cells to surrounding tissues. When excess interstitial fluid accumulates and causes tissue swelling, the anchoring filaments are pulled, making the openings between cells even larger so that more fluid can flow into the lymphatic capillary.[1]

text: Lymph capillaries have a greater internal oncotic pressure than blood capillaries, due to the greater concentration of plasma proteins in the lymph.