document_title: National Basketball Association

question_text: who has the oldest team in the nba

question_tokens: who has the oldest team in the nba

text: National Basketball Association

text: History

text: Creation and merger

text: The Basketball Association of America was founded in 1946 by owners of the major ice hockey arenas in the Northeastern and Midwestern United States and Canada. On November 1, 1946, in Toronto, Ontario, Canada, the Toronto Huskies hosted the New York Knickerbockers at Maple Leaf Gardens, in a game the NBA now refers to as the first played game in NBA history.[6] The first basket was made by Ossie Schectman of the Knickerbockers. Although there had been earlier attempts at professional basketball leagues, including the American Basketball League and the NBL, the BAA was the first league to attempt to play primarily in large arenas in major cities. During its early years, the quality of play in the BAA was not significantly better than in competing leagues or among leading independent clubs such as the Harlem Globetrotters. For instance, the 1948 ABL finalist Baltimore Bullets moved to the BAA and won that league's 1948 title, and the 1948 NBL champion Minneapolis Lakers won the 1949 BAA title. Prior to the 1948–49 season, however, NBL teams from Fort Wayne, Indianapolis, Minneapolis, and Rochester jumped to the BAA, which established the BAA as the league of choice for collegians looking to turn professional.[7]

text: On August 3, 1949, the BAA absorbed the remainder of the NBL: Syracuse, Anderson, Tri-Cities, Sheboygan, Denver, and Waterloo. In deference to the merger and to avoid possible legal complications, the league name was changed from the BAA to the National Basketball Association in spite of having the same BAA governing body including Podoloff.[7] The new league had seventeen franchises located in a mix of large and small cities,[8] as well as large arenas and smaller gymnasiums and armories. In 1950, the NBA consolidated to eleven franchises, a process that continued until 1953–54, when the league reached its smallest size of eight franchises: the New York Knicks, Boston Celtics, Philadelphia Warriors, Minneapolis Lakers, Rochester Royals, Fort Wayne Pistons, Tri-Cities Blackhawks, and Syracuse Nationals, all of which remain in the league today. The process of contraction saw the league's smaller-city franchises move to larger cities. The Hawks shifted from the Tri-Cities to Milwaukee in 1951, and then to St. Louis in 1955. The Rochester Royals moved from Rochester, New York, to Cincinnati in 1957 and the Pistons relocated from Fort Wayne, Indiana, to Detroit in 1957.

text: Japanese-American Wataru Misaka broke the NBA color barrier in the 1947–48 season when he played for the New York Knicks. He remained the only non-white player in league history prior to the first African-American, Harold Hunter, signing with the Washington Capitols in 1950.[9][10] Hunter was cut from the team during training camp,[9][11] but several African-American players did play in the league later that year, including Chuck Cooper with the Celtics, Nathaniel "Sweetwater" Clifton with the Knicks, and Earl Lloyd with the Washington Capitols. During this period, the Minneapolis Lakers, led by center George Mikan, won five NBA Championships and established themselves as the league's first dynasty.[12] To encourage shooting and discourage stalling, the league introduced the 24-second shot clock in 1954.[13] If a team does not attempt to score a field goal (or the ball fails to make contact with the rim) within 24 seconds of obtaining the ball, play is stopped and the ball given to its opponent.

text: Celtics' dominance, league expansion and competition

text: In 1957, rookie center Bill Russell joined the Boston Celtics, which already featured guard Bob Cousy and coach Red Auerbach, and went on to lead the club to eleven NBA titles in thirteen seasons. Center Wilt Chamberlain entered the league with the Warriors in 1959 and became a dominant individual star of the 1960s, setting new single game records in scoring (100) and rebounding (55). Russell's rivalry with Chamberlain became one of the greatest rivalries in the history of American team sports.

text: The 1960s were dominated by the Celtics. Led by Russell, Bob Cousy and coach Red Auerbach, Boston won eight straight championships in the NBA from 1959 to 1966. This championship streak is the longest in NBA history. They did not win the title in 1966–67, but regained it in the 1967–68 season and repeated in 1969. The domination totaled nine of the ten championship banners of the 1960s.[14]

text: Through this period, the NBA continued to evolve with the shift of the Minneapolis Lakers to Los Angeles, the Philadelphia Warriors to San Francisco, the Syracuse Nationals to Philadelphia to become the Philadelphia 76ers, and the St. Louis Hawks moving to Atlanta, as well as the addition of its first expansion franchises. The Chicago Packers (now Washington Wizards) became the ninth NBA team in 1961. From 1966 to 1968, the league expanded from 9 to 14 teams, introducing the Chicago Bulls, Seattle SuperSonics (now Oklahoma City Thunder), San Diego Rockets (who relocated to Houston four years later), Milwaukee Bucks, and Phoenix Suns.

text: In 1967, the league faced a new external threat with the formation of the American Basketball Association (ABA). The leagues engaged in a bidding war. The NBA landed the most important college star of the era, Kareem Abdul-Jabbar (then known as Lew Alcindor). However, the NBA's leading scorer, Rick Barry, jumped to the ABA, as did four veteran referees—Norm Drucker, Earl Strom, John Vanak, and Joe Gushue.[15]

text: In 1969, Alan Siegel, who oversaw the design of Jerry Dior's Major League Baseball logo a year prior, created the modern NBA logo inspired by the MLB's. It incorporates the silhouette of the legendary Jerry West based on a photo by Wen Roberts, although NBA officials denied a particular player as being its influence because, according to Siegel, "They want to institutionalize it rather than individualize it. It's become such a ubiquitous, classic symbol and focal point of their identity and their licensing program that they don't necessarily want to identify it with one player." The iconic logo debuted in 1971 and would remain a fixture of the NBA brand.[16][17]

text: The ABA succeeded in signing a number of major stars in the 1970s, including Julius Erving of the Virginia Squires, in part because it allowed teams to sign college undergraduates. The NBA expanded rapidly during this period, one purpose being to tie up the most viable cities. From 1966 to 1974, the NBA grew from nine franchises to 18. In 1970, the Portland Trail Blazers, Cleveland Cavaliers, and Buffalo Braves (now the Los Angeles Clippers) all made their debuts expanding the league to 17.[18] The New Orleans Jazz (now in Utah) came aboard in 1974 bringing the total to 18. Following the 1976 season, the leagues reached a settlement that provided for the addition of four ABA franchises to the NBA, raising the number of franchises in the league at that time to 22. The franchises added were the San Antonio Spurs, Denver Nuggets, Indiana Pacers, and New York Nets (now the Brooklyn Nets). Some of the biggest stars of this era were Kareem Abdul-Jabbar, Rick Barry, Dave Cowens, Julius Erving, Elvin Hayes, Walt Frazier, Moses Malone, Artis Gilmore, George Gervin, Dan Issel, and Pete Maravich. The end of the decade, however, saw declining TV ratings, low attendance and drug-related player issues – both perceived and real – that threatened to derail the league.

text: Surging popularity

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text: The league added the ABA's innovative three-point field goal beginning in 1979 to open up the game. That same year, rookies Larry Bird and Magic Johnson joined the Boston Celtics and Los Angeles Lakers respectively, initiating a period of significant growth in fan interest in the NBA throughout the country and the world. The two had faced each other in the 1979 NCAA Division I Basketball Championship Game, and they would later play against each other in three NBA Finals (1984, 1985 and 1987, featuring 11 players and coaches who would later be inducted to the Basketball Hall of Fame). Like the 1960s, when the Celtics and Lakers faced each other in six NBA Finals, the two teams again dominated the NBA. In the 10 seasons of the 1980s, Johnson led the Lakers to five titles in eight Finals while Bird led the Celtics to three titles in five Finals. Also in the early 1980s, the NBA added one more expansion franchise, the Dallas Mavericks, bringing the total to 23 teams. Later on, Larry Bird won the first three three-point shooting contests. Former league commissioner David Stern, who took office on February 1, 1984, oversaw the expansion and growth of the NBA to a global commodity.

text: Michael Jordan entered the league in 1984 with the Chicago Bulls, providing an even more popular star to support growing interest in the league. This resulted in more cities demanding teams of their own. In 1988 and 1989, four cities got their wishes as the Charlotte Hornets, Miami Heat, Orlando Magic, and Minnesota Timberwolves made their NBA debuts, bringing the total to 27 teams. In the first year of the 1990s, the Detroit Pistons would win the second of their back-to-back titles, led by coach Chuck Daly and guard Isiah Thomas. Jordan and Scottie Pippen would lead the Bulls to two three-peats in eight years during the 1991–98 seasons. Hakeem Olajuwon won back-to-back titles with the Houston Rockets in 1994 and 1995.

text: The 1992 Olympic basketball Dream Team, the first to use current NBA stars, featured Michael Jordan as the anchor, along with Bird, Johnson, David Robinson, Patrick Ewing, Scottie Pippen, Clyde Drexler, Karl Malone, John Stockton, Chris Mullin, Charles Barkley, and star NCAA amateur Christian Laettner. The team was elected to the Naismith Memorial Basketball Hall of Fame, while 11 of the 12 players on the roster (all but Laettner) and three of the four coaches have been elected to the Hall of Fame as individuals.

text: In 1995, the NBA expanded to Canada with the addition of the Vancouver Grizzlies and the Toronto Raptors. In 2001, the Vancouver Grizzlies relocated to Memphis, which left the Raptors as the only Canadian team in the NBA.

text: In 1996, the NBA created a women's league, the Women's National Basketball Association (WNBA).

text: In 1998, the NBA owners began a lockout which lasted 191 days and was settled on January 18, 1999. As a result of this lockout the 1998–99 NBA season was reduced from 82 to 50 games (61% of a normal season), and the All-Star Game was cancelled. The San Antonio Spurs won their first championship, and first by a former ABA team, by beating the New York Knicks, who were the first, and are the only, eighth seed to ever make it to the NBA Finals.

text: Modern era

text: Since the breakup of the Chicago Bulls championship roster in the summer of 1998, the Western Conference has dominated, with the Los Angeles Lakers and San Antonio Spurs combining to win the title nine out of fourteen seasons. Tim Duncan and David Robinson won the 1999 championship with the Spurs, and Shaquille O'Neal and Kobe Bryant started the 2000s with three consecutive championships for the Lakers. The Spurs reclaimed the title in 2003 against the Nets. In 2004, the Lakers returned to the Finals, only to fall in five games to the Detroit Pistons.

text: After the Spurs took home the Larry O'Brien Championship Trophy in 2005, the 2006 Finals featured two franchises making their inaugural Finals appearances. The Miami Heat, led by their star shooting guard, Dwyane Wade, and Shaquille O'Neal, who had been traded from the Lakers during the 2004 summer, won the series over the Dallas Mavericks in six after losing the first two games. The Lakers/Spurs dominance continued in 2007 with a four-game sweep by the Spurs over the Cleveland Cavaliers, who were led by LeBron James. The 2008 Finals saw a rematch of the league's highest profile rivalry, the Boston Celtics and Los Angeles Lakers, with the Celtics winning, for their 17th championship, thanks to their new big three of Paul Pierce, Ray Allen, and Kevin Garnett.

text: In 2009, Kobe Bryant and the Lakers returned to the Finals, this time defeating the Dwight Howard-led Orlando Magic. Bryant won his first Bill Russell NBA Finals Most Valuable Player Award in his 13th season after leading the Lakers to their first NBA championship since the departure of Shaquille O'Neal.[19]

text: The 2010 NBA All-Star Game was held at Cowboys Stadium in front of the largest crowd ever, 108,713.[20] At the end of that season, the Celtics and the Lakers renewed their rivalry from 2008 when they met again in the NBA Finals for a record 12th time. The Lakers won the title by winning Game 7, 83–79.[21] Before the start of the 2010–11 season the NBA had an exciting summer with one of the most anticipated free agent classes of all time. Two of which signed, and one resigned, with the Miami Heat, leading to a season that was heavily centered on their eventual success or failure at taking home the championship. The Heat, led by LeBron James, Dwyane Wade, and Chris Bosh, did in fact make the Finals against the Dallas Mavericks, in a rematch for the franchises of the 2006 Finals. The Mavericks, led by Dirk Nowitzki (the eventual NBA Finals MVP), took the series in six games. This was the Mavericks' first title. Veterans Shawn Marion, Jason Kidd, Jason Terry, and Peja Stojaković celebrated their first NBA championship.

text: On July 1, 2011, at 12:01 am, the NBA announced another lockout.[22] After the first few weeks of the season were canceled, the players and owners ratified a new collective bargaining agreement on December 8, 2011, setting up a shortened 66-game season.[23] Following the shortened season, the Miami Heat made a return to the Finals with the trio of Dwyane Wade, LeBron James, and Chris Bosh against Oklahoma City Thunder's Kevin Durant, Russell Westbrook, and James Harden. The Heat went on to defeat the Thunder in five games, capturing their second NBA title in six years. Their success would continue into the following season, which concluded with their victory over the San Antonio Spurs in the 2013 NBA Finals. The two teams would meet for a rematch in the following year's Finals, where the Spurs defeated the Heat in five games. Off the court, commissioner David Stern retired on February 1, 2014, exactly 30 years to the day from taking office. He was succeeded by his deputy, Adam Silver.

text: Following the 2014 Finals, LeBron James announced that he would return to the Cleveland Cavaliers. James led the Cavaliers to their second Finals appearance, where they fell to the Golden State Warriors in six games. The following year, in a rematch, the 2016 NBA Finals concluded with the Cavaliers defeating the Warriors in seven games to win their first NBA Championship. The dominance of those two teams continued in 2017, when the Warriors, having signed Durant as a free agent, took the third straight Finals matchup between the clubs in five games, with Durant named Finals MVP.

text: International influence

text: Following pioneers like Vlade Divac (Serbia) and Dražen Petrović (Croatia) who joined the NBA in the late 1980s, an increasing number of international players have moved directly from playing elsewhere in the world to starring in the NBA. Since 2006, the NBA has faced EuroLeague teams in exhibition matches in the NBA Europe Live Tour, and since 2009, in the EuroLeague American Tour. The 2013–14 season opened with a record 92 international players on the opening night rosters, representing 39 countries and comprising over 20% of the league[24]

text: Other developments

text: In 2001, an affiliated minor league, the National Basketball Development League, now called the NBA G League, was created.[25] Before the league was started, there were strong rumors that the NBA would purchase the Continental Basketball Association, and call it its developmental league.

text: Two years after the Hornets' relocation to New Orleans, the NBA returned to North Carolina, as the Charlotte Bobcats were formed as an expansion team in 2004.

text: The Hornets temporarily relocated to Oklahoma City in 2005 for two seasons because of damage caused by Hurricane Katrina. The team returned to New Orleans in 2007.

text: A new official game ball was introduced on June 28, 2006, for the 2006–07 season, marking the first change to the ball in over 35 years and only the second ball in 60 seasons.[26] Manufactured by Spalding, the new ball featured a new design and new synthetic material that Spalding claimed offered a better grip, feel, and consistency than the original ball. However, many players were vocal in their disdain for the new ball, saying that it was too sticky when dry, and too slippery when wet.

text: Commissioner Stern announced on December 11, 2006, that beginning January 1, 2007, the NBA would return to the traditional leather basketball in use prior to the 2006–07 season. The change was influenced by frequent player complaints and confirmed hand injuries (cuts) caused by the microfiber ball.[27] The Players' Association had filed a suit in behalf of the players against the NBA over the new ball.[28] As of the 2017–18 season, the NBA team jerseys are manufactured by Nike, replacing the previous supplier, Adidas. All teams will wear jerseys with the Nike swoosh logo except the Charlotte Hornets, whose jerseys will instead bear the Jumpman logo associated with longtime Nike endorser Michael Jordan, who owns the Hornets.[29]

text: The Federal Bureau of Investigation (FBI) began an investigation on July 19, 2007, over allegations that veteran NBA referee Tim Donaghy bet on basketball games he officiated over the past two seasons and that he made calls affecting the point spread in those games.[30] On August 15, 2007, Donaghy pleaded guilty to two federal charges related to the investigation. However, he could face additional charges if it is determined that he deliberately miscalled individual games. Donaghy claimed in 2008 that certain refs were friendly with players and "company men" for the NBA. Donaghy alleged that refs influenced the outcome of certain playoff and finals games in 2002 and 2005. NBA commissioner David Stern denied the allegations and said Donaghy was a convicted felon and a "singing, cooperating witness".[31] Donaghy served 15 months in prison and was released in November 2009.[32] According to an independent study by Ronald Beech of Game 6 of the 2002 Western Conference Finals between the Los Angeles Lakers and Sacramento Kings, although the refs increased the Lakers' chances of winning through foul calls during the game, there was no collusion to fix the game. On alleged "star treatment" during Game 6 by the refs toward certain players, Beech claimed, "there does seem to be issues with different standards and allowances for different players." [33]

text: The NBA Board of Governors approved the request of the Seattle SuperSonics to relocate to Oklahoma City on April 18, 2008.[34] The team, however, could not move until it had settled a lawsuit filed by the city of Seattle, which was intended to keep the SuperSonics in Seattle for the remaining two seasons of the team's lease at KeyArena. Following a court case, the city of Seattle settled with the ownership group of the SuperSonics on July 2, 2008, allowing the team to move to Oklahoma City immediately in exchange for terminating the final two seasons of the team's lease at KeyArena.[35] The Oklahoma City Thunder began playing in the 2008–09 season.

text: The first outdoor game in the modern era of the league was played at the Indian Wells Tennis Garden on October 11, 2008, between the Phoenix Suns and the Denver Nuggets.[36]

text: A referee lockout began on September 1, 2009, when the contract between the NBA and its referees expired. The first preseason games were played on October 1, 2009, and replacement referees from the WNBA and NBA Development League were used, the first time replacement referees had been used since the beginning of the 1995–96 season. The NBA and the regular referees reached a deal on October 23, 2009.[37][38]

text: The first official NBA league games on European ground took place in 2011. In two matchups, the New Jersey Nets faced the Toronto Raptors at the O2 Arena in London in front of over 20,000 fans.

text: The NBA laid off around 114 league employees—about 11 percent of all the league office workforce—in July 2011 to save money.[39]

text: The 2011–12 NBA season, scheduled to begin November 1, 2011, with a matchup between the defending champion Dallas Mavericks and the Chicago Bulls, was postponed due to a labor dispute. The lockout officially ended on December 8, 2011, when players and owners ratified a new collective bargaining agreement, and the season began on Christmas Day.

text: The New Jersey Nets officially changed their name to the Brooklyn Nets on April 30, 2012.[40] They began playing in the New York City borough of Brooklyn in the 2012–13 season.

text: The NBA announced in October 2012 that it would begin fining players for flopping.[41][42]

text: After the 2012–13 season, the New Orleans Hornets renamed themselves the Pelicans.[43] During the 2013–14 season, Stern retired as commissioner after 30 years, and deputy commissioner Adam Silver ascended to the position of commissioner. During that season's playoffs, the Bobcats officially reclaimed the Hornets name, and by agreement with the league and the Pelicans, also received sole ownership of all history, records, and statistics from the Pelicans' time in Charlotte. As a result, the Hornets are now officially considered to have been founded in 1988, suspended operations in 2002, and resumed in 2004 as the Bobcats, while the Pelicans are officially treated as a 2002 expansion team.[44] (This is somewhat similar to the relationship between the Cleveland Browns and Baltimore Ravens in the NFL.)

text: Donald Sterling, who was then-owner of the Los Angeles Clippers, received a lifetime ban from the NBA on April 29, 2014, after racist remarks he made became public. Sterling was also fined US$2.5 million, the maximum allowed under the NBA Constitution.[45]

text: Becky Hammon was hired by the San Antonio Spurs on August 5, 2014, as an assistant coach, becoming the second female coach in NBA history but the first full-time coach.[46][47] This also makes her the first full-time female coach in any of the four major professional sports in North America.[47]

text: The NBA announced on April 15, 2016, that it would allow all 30 of its member clubs to sell corporate sponsor advertisement patches on official game uniforms, beginning with the 2017–18 season. The sponsorship advertisement patches would appear on the left front of jerseys, opposite Nike's logo, and would measure approximately 2.5 by 2.5 inches. The NBA will become the first major North American professional sports league to allow corporate sponsorship logos on official team uniforms.[48] The first team to announce a jersey sponsorship was the Philadelphia 76ers, who agreed to a deal with StubHub.[49]

text: On July 6, 2017, the NBA unveiled an updated rendition of its logo; it is largely identical to the previous design, except with revised typography and a "richer" color scheme. The league began to phase in the updated logo across its properties during the 2017 NBA Summer League, but it will not immediately be used on equipment or uniforms due to lead time.[50]

text: The NBA also officially released new Nike uniforms for all 30 teams for the 2017–18 season. In the press release, the league stated it would do away with "home" and "away" uniform designations. Instead, each team would have four uniforms: the "Association" edition, which is the team's traditional white uniform, the "Icon" edition, which is the team's primary color uniform, and two other uniform editions, to be unveiled at a later date.[51]

text: Teams

text:
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text: The NBA originated in 1946 with 11 teams, and through a sequence of team expansions, reductions, and relocations currently consists of 30 teams. The United States is home to 29 teams and one is located in Canada.

text: The current league organization divides thirty teams into two conferences of three divisions with five teams each. The current divisional alignment was introduced in the 2004–05 season. Reflecting the population distribution of the United States and Canada as a whole, most teams are in the eastern half of the country: thirteen teams are in the Eastern Time Zone, nine in the Central, three in the Mountain, and five in the Pacific.

text:
Division
Team
City
Arena
Capacity
Coordinates
Founded
Joined
Head coach

Eastern Conference

Atlantic
Boston Celtics
Boston, MA
TD Garden
18,624
42°21′59″N 71°03′44″W / 42.366303°N 71.062228°W / 42.366303; -71.062228 (Boston Celtics)
1946
Brad Stevens

Brooklyn Nets
New York City, NY
Barclays Center
17,732
40°40′58″N 73°58′29″W / 40.68265°N 73.974689°W / 40.68265; -73.974689 (Brooklyn Nets)
1967*
1976
Kenny Atkinson

New York Knicks
Madison Square Garden
19,812
40°45′02″N 73°59′37″W / 40.750556°N 73.993611°W / 40.750556; -73.993611 (New York Knicks)
1946
Jeff Hornacek

Philadelphia 76ers
Philadelphia, PA
Wells Fargo Center
21,600
39°54′04″N 75°10′19″W / 39.901111°N 75.171944°W / 39.901111; -75.171944 (Philadelphia 76ers)
1946*
1949
Brett Brown

Toronto Raptors
Toronto, ON
Air Canada Centre
19,800
43°38′36″N 79°22′45″W / 43.643333°N 79.379167°W / 43.643333; -79.379167 (Toronto Raptors)
1995
Dwane Casey

Central
Chicago Bulls
Chicago, IL
United Center
20,917
41°52′50″N 87°40′27″W / 41.880556°N 87.674167°W / 41.880556; -87.674167 (Chicago Bulls)
1966
Fred Hoiberg

Cleveland Cavaliers
Cleveland, OH
Quicken Loans Arena
20,562
41°29′47″N 81°41′17″W / 41.496389°N 81.688056°W / 41.496389; -81.688056 (Cleveland Cavaliers)
1970
Tyronn Lue

Detroit Pistons
Detroit, MI
Little Caesars Arena
20,491
42°41′49″N 83°14′44″W / 42.696944°N 83.245556°W / 42.696944; -83.245556 (Detroit Pistons)
1941*
1948
Stan Van Gundy

Indiana Pacers
Indianapolis, IN
Bankers Life Fieldhouse
17,923
39°45′50″N 86°09′20″W / 39.763889°N 86.155556°W / 39.763889; -86.155556 (Indiana Pacers)
1967
1976
Nate McMillan

Milwaukee Bucks
Milwaukee, WI
Bradley Center
18,717
43°02′37″N 87°55′01″W / 43.043611°N 87.916944°W / 43.043611; -87.916944 (Milwaukee Bucks)
1968
Jason Kidd

Southeast
Atlanta Hawks
Atlanta, GA
Philips Arena
15,711
33°45′26″N 84°23′47″W / 33.757222°N 84.396389°W / 33.757222; -84.396389 (Atlanta Hawks)
1946*
1949
Mike Budenholzer

Charlotte Hornets
Charlotte, NC
Spectrum Center
19,077
35°13′30″N 80°50′21″W / 35.225°N 80.839167°W / 35.225; -80.839167 (Charlotte Hornets)
1988*
Steve Clifford

Miami Heat
Miami, FL
American Airlines Arena
19,600
25°46′53″N 80°11′17″W / 25.781389°N 80.188056°W / 25.781389; -80.188056 (Miami Heat)
1988
Erik Spoelstra

Orlando Magic
Orlando, FL
Amway Center
18,846
28°32′21″N 81°23′01″W / 28.539167°N 81.383611°W / 28.539167; -81.383611 (Orlando Magic)
1989
Frank Vogel

Washington Wizards
Washington, D.C.
Capital One Arena
20,356
38°53′53″N 77°01′15″W / 38.898056°N 77.020833°W / 38.898056; -77.020833 (Washington Wizards)
1961*
Scott Brooks

Western Conference

Northwest
Denver Nuggets
Denver, CO
Pepsi Center
19,520
39°44′55″N 105°00′27″W / 39.748611°N 105.0075°W / 39.748611; -105.0075 (Denver Nuggets)
1967
1976
Michael Malone

Minnesota Timberwolves
Minneapolis, MN
Target Center
19,356
44°58′46″N 93°16′34″W / 44.979444°N 93.276111°W / 44.979444; -93.276111 (Minnesota Timberwolves)
1989
Tom Thibodeau

Oklahoma City Thunder
Oklahoma City, OK
Chesapeake Energy Arena
18,203
35°27′48″N 97°30′54″W / 35.463333°N 97.515°W / 35.463333; -97.515 (Oklahoma City Thunder)
1967*
Billy Donovan

Portland Trail Blazers
Portland, OR
Moda Center
19,441
45°31′54″N 122°40′00″W / 45.531667°N 122.666667°W / 45.531667; -122.666667 (Portland Trail Blazers)
1970
Terry Stotts

Utah Jazz
Salt Lake City, UT
Vivint Smart Home Arena
19,911
40°46′06″N 111°54′04″W / 40.768333°N 111.901111°W / 40.768333; -111.901111 (Utah Jazz)
1974*
Quin Snyder

Pacific
Golden State Warriors
Oakland, CA
Oracle Arena
19,596
37°45′01″N 122°12′11″W / 37.750278°N 122.203056°W / 37.750278; -122.203056 (Golden State Warriors)
1946*
Steve Kerr

Los Angeles Clippers
Los Angeles, CA
Staples Center
19,060
34°02′35″N 118°16′02″W / 34.043056°N 118.267222°W / 34.043056; -118.267222 (Los Angeles Clippers)
1970*
Doc Rivers

Los Angeles Lakers
18,997
34°02′35″N 118°16′02″W / 34.043056°N 118.267222°W / 34.043056; -118.267222 (Los Angeles Lakers)
1947*
1948
Luke Walton

Phoenix Suns
Phoenix, AZ
Talking Stick Resort Arena
18,055
33°26′45″N 112°04′17″W / 33.445833°N 112.071389°W / 33.445833; -112.071389 (Phoenix Suns)
1968
Jay Triano

Sacramento Kings
Sacramento, CA
Golden 1 Center
17,500
38°38′57″N 121°31′05″W / 38.649167°N 121.518056°W / 38.649167; -121.518056 (Sacramento Kings)
1923*
1948
Dave Joerger

Southwest
Dallas Mavericks
Dallas, TX
American Airlines Center
19,200
32°47′26″N 96°48′37″W / 32.790556°N 96.810278°W / 32.790556; -96.810278 (Dallas Mavericks)
1980
Rick Carlisle

Houston Rockets
Houston, TX
Toyota Center
18,055
29°45′03″N 95°21′44″W / 29.750833°N 95.362222°W / 29.750833; -95.362222 (Houston Rockets)
1967*
Mike D'Antoni

Memphis Grizzlies
Memphis, TN
FedExForum
18,119
35°08′18″N 90°03′02″W / 35.138333°N 90.050556°W / 35.138333; -90.050556 (Memphis Grizzlies)
1995*
David Fizdale

New Orleans Pelicans
New Orleans, LA
Smoothie King Center
16,867
29°56′56″N 90°04′55″W / 29.948889°N 90.081944°W / 29.948889; -90.081944 (New Orleans Pelicans)
2002*
Alvin Gentry

San Antonio Spurs
San Antonio, TX
AT&T Center
18,418
29°25′37″N 98°26′15″W / 29.426944°N 98.4375°W / 29.426944; -98.4375 (San Antonio Spurs)
1967*
1976
Gregg Popovich

text:
An asterisk (*) denotes a franchise move. See the respective team articles for more information.
The Fort Wayne Pistons, Minneapolis Lakers and Rochester Royals all joined the NBA (BAA) in 1948 from the NBL.
The Syracuse Nationals and Tri-Cities Blackhawks joined the NBA in 1949 as part of the BAA-NBL absorption.
The Indiana Pacers, New York Nets, San Antonio Spurs, and Denver Nuggets all joined the NBA in 1976 as part of the NBA-ABA merger.
The Charlotte Hornets are regarded as a continuation of the original Charlotte franchise. Because of this, the New Orleans Pelicans are no longer the same franchise as the original Charlotte Hornets. The Hornets were known as the Bobcats from 2004–2014. The New Orleans Pelicans were established in 2002. The Charlotte Hornets rejoined the league in 2004.

tag: ol

text: Regular season

text: Following the summer break, teams begin training camps in late September. Training camps allow the coaching staff to evaluate players (especially rookies), scout the team's strengths and weaknesses, prepare the players for the rigorous regular season, and determine the 12-man active roster (and a 3-man inactive list) with which they will begin the regular season. Teams have the ability to assign players with less than two years of experience to the NBA G League. After training camp, a series of preseason exhibition games are held. Preseason matches are sometimes held in non-NBA cities, both in the United States and overseas. The NBA regular season begins in the last week of October.

text: During the regular season, each team plays 82 games, 41 each home and away. A team faces opponents in its own division four times a year (16 games). Each team plays six of the teams from the other two divisions in its conference four times (24 games), and the remaining four teams three times (12 games). Finally, each team plays all the teams in the other conference twice apiece (30 games). This asymmetrical structure means the strength of schedule will vary between teams (but not as significantly as the NFL or MLB). Over five seasons, each team will have played 80 games against their division (20 games against each opponent, 10 at home, 10 on the road), 180 games against the rest of their conference (18 games against each opponent, 9 at home, 9 on the road), and 150 games against the other conference (10 games against each team, 5 at home, 5 on the road).

text: The NBA is one of only two of the four major professional sports leagues in the United States and Canada in which teams play every other team during the regular season (the other being the National Hockey League). Each team hosts and visits every other team at least once every season. From 2005 to 2008, the NBA had the distinction of being the only one of the four major leagues in which all teams play every other team.

text: The NBA is also the only league that regularly schedules games on Christmas Day.[52] The league has been playing games regularly on the holiday since 1947,[53] though the first Christmas Day games were not televised until 1983–84.[54] Games played on this day have featured some of the best teams and players.[52][53][54] Christmas is also notable for NBA on television, as the holiday is when the first NBA games air on network television each season.[53][54] Games played on this day have been some of the highest-rated games during a particular season.

text: In February, the regular season pauses to celebrate the annual NBA All-Star Game. Fans vote throughout the United States, Canada, and on the Internet, and the top vote-getters at each position in each conference are given a starting spot on their conference's All-Star team. Coaches vote to choose the remaining 14 All-Stars. Then, Eastern conference players face the Western conference players in the All-Star game. The player with the best performance during the game is rewarded with a Game MVP award. Other attractions of the All-Star break include the Rising Stars Challenge (originally Rookie Challenge), where the top rookies and second-year players in the NBA play in a 5-on-5 basketball game, with the current format pitting U.S. players against those from the rest of the world; the Skills Challenge, where players compete to finish an obstacle course consisting of shooting, passing, and dribbling in the fastest time; the Three Point Contest, where players compete to score the highest number of three-point field goals in a given time; and the NBA Slam Dunk Contest, where players compete to dunk the ball in the most entertaining way according to the judges. These other attractions have varying names which include the names of the various sponsors who have paid for naming rights.

text: Shortly after the All-Star break is the trade deadline, which is set to fall on the 16th Thursday of the season (usually in February) at 3pm Eastern Time.[55] After this date, teams are not allowed to exchange players with each other for the remainder of the season, although they may still sign and release players. Major trades are often completed right before the trading deadline, making that day a hectic time for general managers.

text: Around the middle of April, the regular season ends. It is during this time that voting begins for individual awards, as well as the selection of the honorary, league-wide, post-season teams. The Sixth Man of the Year Award is given to the best player coming off the bench (must have more games coming off the bench than actual games started). The Rookie of the Year Award is awarded to the most outstanding first-year player. The Most Improved Player Award is awarded to the player who is deemed to have shown the most improvement from the previous season. The Defensive Player of the Year Award is awarded to the league's best defender. The Coach of the Year Award is awarded to the coach that has made the most positive difference to a team. The Most Valuable Player Award is given to the player deemed the most valuable for (his team) that season. Additionally, Sporting News awards an unofficial (but widely recognized) Executive of the Year Award to the general manager who is adjudged to have performed the best job for the benefit of his franchise.

text: The post-season teams are the All-NBA Team, the All-Defensive Team, and the All-Rookie Team; each consists of five players. There are three All-NBA teams, consisting of the top players at each position, with first-team status being the most desirable. There are two All-Defensive teams, consisting of the top defenders at each position. There are also two All-Rookie teams, consisting of the top first-year players regardless of position.

text: Playoffs

text: The NBA Playoffs begin in late April, with the top eight teams in each conference, regardless of divisional alignment, competing for the Championship. Seeds are awarded in strict order of regular-season record (with a tiebreaker system used as needed).

text: Having a higher seed offers several advantages. Since the first seed begins the playoffs playing against the eighth seed, the second seed plays the seventh seed, the third seed plays the sixth seed, and the fourth seed plays the fifth seed, having a higher seed means a team faces a weaker team in the first round. The team in each series with the better record has home court advantage, including the First Round. Before the league changed its playoff determination format for the 2006–07 season, this meant that, for example, if the team that received the 6 seed had a better record than the team with the 3 seed (by virtue of a divisional championship), the 6 seed would have home court advantage, even though the other team had a higher seed. Therefore, the team with the best regular season record in the league is guaranteed home court advantage in every series it plays. For example, in 2006, the Denver Nuggets won 44 games and captured the Northwest Division and the #3 seed. Their opponent was the #6 seed Los Angeles Clippers, who won 47 games and finished second in the Pacific Division. Although Denver won its much weaker division, the Clippers had home-court advantage and won the series in 5.

text: The playoffs follow a tournament format. Each team plays an opponent in a best-of-seven series, with the first team to win four games advancing into the next round, while the other team is eliminated from the playoffs. In the next round, the successful team plays against another advancing team of the same conference. All but one team in each conference are eliminated from the playoffs. Since the NBA does not re-seed teams, the playoff bracket in each conference uses a traditional design, with the winner of the series matching the 1st and 8th seeded teams playing the winner of the series matching the 4th and 5th seeded teams, and the winner of the series matching the 2nd and 7th seeded teams playing the winner of the series matching the 3rd and 6th seeded teams. In every round, the best-of-7 series follows a 2–2–1–1–1 home-court pattern, meaning that one team will have home court in games 1, 2, 5, and 7, while the other plays at home in games 3, 4, and 6. From 1985 to 2013, the NBA Finals followed a 2–3–2 pattern, meaning that one team had home court in games 1, 2, 6, and 7, while the other played at home in games 3, 4, and 5.[56]

text: The final playoff round, a best-of-seven series between the victors of both conferences, is known as the NBA Finals, and is held annually in June. The victor in the NBA Finals wins the Larry O'Brien Championship Trophy. Each player and major contributor—including coaches and the general manager—on the winning team receive a championship ring. In addition, the league awards the Bill Russell NBA Finals Most Valuable Player Award to the best performing player of the series.

text: On August 2, 2006, the NBA announced a new playoff format. The new format took the three division winners and the second-place team with the best record in each conference, and ranked them 1–4 by record. The other slots in each conference were filled by the four remaining teams with the best records.[57] Previously, the top three seeds went to the division winners. The league began using its current format, with the top eight teams in each conference advancing regardless of divisional alignment, in the 2015–16 season.[58]

text: League championships

text: The Boston Celtics have won the most championships with 17 NBA Finals wins. The second most successful franchise is the Los Angeles Lakers, who have 16 overall championships (11 in Los Angeles, 5 in Minneapolis). Following the Lakers, are the Chicago Bulls with six championships, all won over an 8-year span during the 1990s. The San Antonio Spurs have five championships, all since 1999, and the Golden State Warriors also have five championships overall (2 in Philadelphia, 3 in Oakland).

text:
Teams
Win
Loss
Total
Year(s) won
Year(s) lost

Boston Celtics
17
4
21
1957, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1968, 1969, 1974, 1976, 1981, 1984, 1986, 2008
1958, 1985, 1987, 2010

Minneapolis/Los Angeles Lakers
16
15
31
1949, 1950, 1952, 1953, 1954, 1972, 1980, 1982, 1985, 1987, 1988, 2000, 2001, 2002, 2009, 2010
1959, 1962, 1963, 1965, 1966, 1968, 1969, 1970, 1973, 1983, 1984, 1989, 1991, 2004, 2008

Chicago Bulls
6
0
6
1991, 1992, 1993, 1996, 1997, 1998
—

Philadelphia/San Francisco/Golden State Warriors
5
4
9
1947, 1956, 1975, 2015, 2017
1948, 1964, 1967, 2016

San Antonio Spurs
5
1
6
1999, 2003, 2005, 2007, 2014
2013

Syracuse Nationals/Philadelphia 76ers
3
6
9
1955, 1967, 1983
1950, 1954, 1977, 1980, 1982, 2001

Fort Wayne/Detroit Pistons
3
4
7
1989, 1990, 2004
1955, 1956, 1988, 2005

Miami Heat
3
2
5
2006, 2012, 2013
2011, 2014

New York Knicks
2
6
8
1970, 1973
1951, 1952, 1953, 1972, 1994, 1999

Houston Rockets
2
2
4
1994, 1995
1981, 1986

St. Louis/Atlanta Hawks
1
3
4
1958
1957, 1960, 1961

Baltimore/Washington Bullets (now Washington Wizards)
1
3
4
1978
1971, 1975, 1979

Seattle SuperSonics/Oklahoma City Thunder
1
3
4
1979
1978, 1996, 2012

Cleveland Cavaliers
1
3
4
2016
2007, 2015, 2017

Portland Trail Blazers
1
2
3
1977
1990, 1992

Milwaukee Bucks
1
1
2
1971
1974

Dallas Mavericks
1
1
2
2011
2006

Baltimore Bullets (original) (folded in 1954)
1
0
1
1948
—

Rochester Royals (now Sacramento Kings)
1
0
1
1951
—

Phoenix Suns
0
2
2
—
1976, 1993

Orlando Magic
0
2
2
—
1995, 2009

Utah Jazz (formerly New Orleans Jazz)
0
2
2
—
1997, 1998

New Jersey Nets (now Brooklyn Nets)
0
2
2
—
2002, 2003

Chicago Stags (folded in 1950)
0
1
1
—
1947

Washington Capitols (folded in 1951)
0
1
1
—
1949

Indiana Pacers
0
1
1
—
2000

text: Current teams that have no NBA Finals appearances:

text:
Charlotte Hornets (formerly Charlotte Bobcats)
Denver Nuggets
Los Angeles Clippers (formerly Buffalo Braves, San Diego Clippers)
Memphis Grizzlies (formerly Vancouver Grizzlies)
Minnesota Timberwolves
New Orleans Pelicans (formerly New Orleans Hornets, New Orleans/Oklahoma City Hornets)
Toronto Raptors

text: Media coverage

text: As one of the major sports leagues in North America, the National Basketball Association has a long history of partnership with television networks in the United States. The League signed a contract with DuMont in its 8th season (1953–54), marking the first year the NBA had a national television broadcaster. Similar to NFL, the lack of television stations leads to NBC taking over the rights beginning the very next season until April 7, 1962 - NBC's first tenure with the NBA. Currently in the U.S., the NBA has a contract with ESPN and TNT through the 2024–25 season. Games that are not broadcast nationally are usually aired over regional sports network specific to the area where the teams are located.

text: International competitions

text: The National Basketball Association has sporadically participated in international club competitions. From 1987 to 1999 the NBA champions played against the continental champions of the Fédération Internationale de Basketball (FIBA) in the McDonald's Championship. This tournament was won by the NBA invitee every year it was held.[59]

text: Ticket prices and viewership demographics

text: In 2012, a ticket cost from $10 to $3,000 apiece, depending on the location of the seat and the success of the teams that were playing.[60]

text: Viewership demographics

text: According to Nielsen's survey, the NBA has the youngest audience, with 45 percent of its viewers under 35, but the least likely, along with Major League Baseball, to be watched by women, who make up only 30% of the viewership. It also has the highest share of black viewers with 45 percent of its viewers being black and only about 40 percent of viewers being white, making it the only top North American sport that doesn't have a white majority audience.[61]

text: Notable people

text: Presidents and commissioners

text:
Maurice Podoloff, President from 1946 to 1963
Walter Kennedy, President from 1963 to 1967 and Commissioner from 1967 to 1975
Larry O'Brien, Commissioner from 1975 to 1984
David Stern, Commissioner from 1984 to 2014
Adam Silver, Commissioner from 2014 to present

text: Players

text:
50 Greatest Players in NBA History
Lists of National Basketball Association players

List of foreign NBA players, a list that is exclusively for players who are not from the United States

text: Foreign players

text: International influence

text: Following pioneers like Vlade Divac (Serbia) and Dražen Petrović (Croatia) who joined the NBA in the late 1980s, an increasing number of international players have moved directly from playing elsewhere in the world to starring in the NBA. Below is a short list of foreign players who have won NBA awards or have been otherwise recognized for their contributions to basketball, either currently or formerly active in the league:

text:
Šarūnas Marčiulionis, Lithuania – 2014 inductee into the Naismith Memorial Basketball Hall of Fame. First Soviet Union and one of the very first Europeans to sign contract with NBA club and to play solidly in the league, helping to lead the way for the internationalization of the league in the late 1990s.
Toni Kukoč, Croatia – 3-time NBA Champion with Chicago Bulls (1996, 1997, 1998), named in 2008 as one of the 50 Greatest EuroLeague Contributors
Vlade Divac, Serbia – 2-time Olympic silver medalist, 2001 NBA All-Star, 2-time World Champion, 3-time European Champion, 50 Greatest EuroLeague Contributors
Arvydas Sabonis, Lithuania – 2011 inductee into the Naismith Memorial Basketball Hall of Fame, 1984, 1985, 1988, 1995, 1999 Euroscar Player of the Year, 1985, 1997 Mr. Europa Player of the Year, Olympic gold medalist in 1988 with the Soviet Union and bronze medalist in 1992 and 1996 with Lithuania, 1996 NBA All-Rookie First Team, 50 Greatest EuroLeague Contributors
Dirk Nowitzki, Germany – NBA Champion with Dallas Mavericks (2011), MVP of the 2002 FIBA World Championship and EuroBasket 2005, member of the all-tournament team in the 2002 FIBA World Championship, 2002–2006 and 2011 Euroscar winner, 2005 Mr. Europa, 2005 and 2011 FIBA Europe Player of the Year, 2007 NBA MVP, 2011 Bill Russell NBA Finals Most Valuable Player Award, 2006 NBA Three-Point Shootout champion and 11-time NBA All-Star (entered the NBA in 1998)
Hedo Türkoğlu, Turkey – 2008 Most Improved Player Award winner, member of the all-tournament team in the 2010 FIBA World Championship (entered the NBA in 2000)
Pau Gasol, Spain – 2-time NBA Champion with Los Angeles Lakers (2009 & 2010), Three time NBA All-Star, 2002 NBA Rookie of the Year, 2004 and 2009 Mr. Europa, 2006 FIBA World Championship MVP, 2008 and 2009 Euroscar and FIBA Europe Player of the Year, EuroBasket 2009 MVP, winner of the NBA Citizenship Award in 2012 (entered the NBA in 2001)
Andrei Kirilenko, Russia – EuroBasket 2007 MVP, 2007 FIBA Europe Player of the Year (drafted in 1999, played in the NBA from 2001 to 2011 before returning to Russia due to the lockout, returned in 2012 as a member of the Minnesota Timberwolves.)
Tony Parker, France – 4-time NBA Champion with the Spurs, 2007 NBA Finals MVP and 2007 Euroscar winner (entered the NBA in 2001)
Manu Ginóbili, Argentina – 4-time NBA Champion with San Antonio Spurs, 2008 Sixth Man Award winner, 50 Greatest EuroLeague Contributors, gold medal in the 2004 Summer Olympics with Argentina (drafted in 1999, entered the NBA in 2002)
Yao Ming, China – First pick in the 2002 NBA draft and 7-time NBA All-Star (played in the NBA from 2002 to 2011)
Leandro Barbosa, Brazil – NBA Champion with Golden State Warriors (2015),[62] 2007 Sixth Man Award winner (entered the NBA in 2003)
Andrea Bargnani, Italy – First pick in the 2006 NBA draft by the Toronto Raptors (entered the NBA in 2006)

text: On some occasions, young players, most but not all from the English-speaking world, have attended U.S. colleges before playing in the NBA. Notable examples are:

text:
Nigerian Hakeem Olajuwon (top draft pick in 1984, 2-time champion, 12-time All-Star, 1994 MVP, 1994 and 1995 Finals MVP, 1994 and 1995 Defensive Player of the Year, only player to receive the MVP Award, Defensive Player of the Year Award, and Finals MVP award in the same season, and Hall of Famer)
Congolese Dikembe Mutombo (Four time NBA Defensive Player of the Year, selected fourth overall by the Denver Nuggets in the 1991 NBA Draft and 8-time NBA All-Star)
Dutchman Rik Smits (1988 second overall pick, 1998 NBA All-Star, played 12 years for the Indiana Pacers)
German Detlef Schrempf (Sixth Man Award winner in 1991 and 1992, 3-time All-Star)
Canadian Steve Nash (2005 and 2006 MVP)
Australians Luc Longley (3-time champion with the Bulls in the 1990s) and Andrew Bogut, (top draft pick in 2005).
Sudanese-born Englishman Luol Deng (2007 winner of the NBA Sportsmanship Award)

text: Since 2006, the NBA has faced EuroLeague teams in exhibition matches in the NBA Europe Live Tour, and since 2009 in the EuroLeague American Tour.

text: The 2013–14 season opened with a record 92 international players on the opening night rosters, representing 39 countries and comprising over 20% of the league[24] The NBA defines "international" players as those born outside the 50 United States and Washington, D.C. This means that:

text:
Players born in U.S. possessions such as Puerto Rico and the U.S., Virgin Islands, most notably USVI native Tim Duncan, are counted as "international" even though they are U.S. citizens by birth, and may even have represented the U.S. in international competition (like Duncan).
U.S.-born players are not counted as "international" even if they were born with citizenship in another country and represent that country internationally, such as Joakim Noah, and Kosta Koufos.

text: Coaches

text:
List of current National Basketball Association head coaches
List of National Basketball Association head coaches
List of National Basketball Association player-coaches
List of NBA championship head coaches
List of foreign NBA coaches
Top 10 Coaches in NBA History


document_title: Sperm

question_text: where are the mitochondria located in the sperm

root

text: Sperm

text: Sperm in animals

text: Function

text: The main sperm function is to reach the ovum and fuse with it to deliver two sub-cellular structures: (i) the male pronucleus that contains the genetic material and (ii) the centrioles that are structures that help organize the microtubule cytoskeleton.

tag: p

text: Anatomy

text: The mammalian sperm cell consists of a head, neck, a midpiece and a tail. The head contains the nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome, which contains enzymes used for penetrating the female egg. The neck contains the sperm centriole. The midpiece has a central filamentous core with many mitochondria spiralled around it, used for ATP production for the journey through the female cervix, uterus and uterine tubes. The tail or "flagellum" executes the lashing movements that propel the spermatocyte.[1]

text: During fertilization, the sperm provides three essential parts to the oocyte: (1) a signalling or activating factor, which causes the metabolically dormant oocyte to activate; (2) the haploid paternal genome; (3) the centriole, which is responsible for forming the centrosome and microtubule system.[2]

text: Origin

text: The spermatozoa of animals are produced through spermatogenesis inside the male gonads (testicles) via meiotic division. The initial spermatozoon process takes around 70 days to complete. The spermatid stage is where the sperm develops the familiar tail. The next stage where it becomes fully mature takes around 60 days when it is called a spermatozoan.[3] Sperm cells are carried out of the male body in a fluid known as semen. Human sperm cells can survive within the female reproductive tract for more than 5 days post coitus.[4] Semen is produced in the seminal vesicles, prostate gland and urethral glands.

text: In 2016 scientists at Nanjing Medical University claimed they had produced cells resembling mouse spermatids artificially from stem cells. They injected these spermatids into mouse eggs and produced pups.[5]

text: Sperm quality

text: Sperm quantity and quality are the main parameters in semen quality, which is a measure of the ability of semen to accomplish fertilization. Thus, in humans, it is a measure of fertility in a man. The genetic quality of sperm, as well as its volume and motility, all typically decrease with age.[6] (See paternal age effect.)

text: DNA damages present in sperm cells in the period after meiosis but before fertilization may be repaired in the fertilized egg, but if not repaired, can have serious deleterious effects on fertility and the developing embryo. Human sperm cells are particularly vulnerable to free radical attack and the generation of oxidative DNA damage.[7] (see e.g. 8-Oxo-2'-deoxyguanosine)

text: The postmeiotic phase of mouse spermatogenesis is very sensitive to environmental genotoxic agents, because as male germ cells form mature sperm they progressively lose the ability to repair DNA damage.[8] Irradiation of male mice during late spermatogenesis can induce damage that persists for at least 7 days in the fertilizing sperm cells, and disruption of maternal DNA double-strand break repair pathways increases sperm cell-derived chromosomal aberrations.[9] Treatment of male mice with melphalan, a bifunctional alkylating agent frequently employed in chemotherapy, induces DNA lesions during meiosis that may persist in an unrepaired state as germ cells progress though DNA repair-competent phases of spermatogenic development.[10] Such unrepaired DNA damages in sperm cells, after fertilization, can lead to offspring with various abnormalities.

text: Sperm size

text: Related to sperm quality is sperm size, at least in some animals. For instance, the sperm of some species of fruit fly (Drosophila) are up to 5.8 cm long — about 20 times as long as the fly itself. Longer sperm cells are better than their shorter counterparts at displacing competitors from the female’s seminal receptacle. The benefit to females is that only healthy males carry ‘good’ genes that can produce long sperm in sufficient quantities to outcompete their competitors.[11][12]

text: Market for human sperm

text: Some sperm banks hold up to 170 litres (37 imp gal; 45 US gal) of sperm.[13]

text: In addition to ejaculation, it is possible to extract sperm through TESE.

text: On the global market, Denmark has a well-developed system of human sperm export. This success mainly comes from the reputation of Danish sperm donors for being of high quality[14] and, in contrast with the law in the other Nordic countries, gives donors the choice of being either anonymous or non-anonymous to the receiving couple.[14] Furthermore, Nordic sperm donors tend to be tall and highly educated[15] and have altruistic motives for their donations,[15] partly due to the relatively low monetary compensation in Nordic countries. More than 50 countries worldwide are importers of Danish sperm, including Paraguay, Canada, Kenya, and Hong Kong.[14] However, the Food and Drug Administration (FDA) of the US has banned import of any sperm, motivated by a risk of transmission of Creutzfeldt–Jakob disease, although such a risk is insignificant, since artificial insemination is very different from the route of transmission of Creutzfeldt–Jakob disease.[16] The prevalence of Creutzfeldt–Jakob disease for donors is at most one in a million, and if the donor was a carrier, the infectious proteins would still have to cross the blood-testis barrier to make transmission possible.[16]

text: History

text: Sperm were first observed in 1677 by Antonie van Leeuwenhoek[17] using a microscope, he described them as being animalcules (little animals), probably due to his belief in preformationism, which thought that each sperm contained a fully formed but small human.[citation needed]

text: Forensic analysis

text: Ejaculated fluids are detected by ultraviolet light, irrespective of the structure or colour of the surface.[18] Sperm heads, e.g. from vaginal swabs, are still detected by microscopy using the "Christmas Tree Stain" method, i.e., Kernechtrot-Picroindigocarmine (KPIC) staining.[19][20]

text: Sperm in plants

text: Sperm cells in algal and many plant gametophytes are produced in male gametangia (antheridia) via mitotic division. In flowering plants, sperm nuclei are produced inside pollen.[citation needed]

text: Motile sperm cells

text: Motile sperm cells typically move via flagella and require a water medium in order to swim toward the egg for fertilization. In animals most of the energy for sperm motility is derived from the metabolism of fructose carried in the seminal fluid. This takes place in the mitochondria located in the sperm's midpiece (at the base of the sperm head). These cells cannot swim backwards due to the nature of their propulsion. The uniflagellated sperm cells (with one flagellum) of animals are referred to as spermatozoa, and are known to vary in size.[citation needed]

text: Motile sperm are also produced by many protists and the gametophytes of bryophytes, ferns and some gymnosperms such as cycads and ginkgo. The sperm cells are the only flagellated cells in the life cycle of these plants. In many ferns and lycophytes, they are multi-flagellated (carrying more than one flagellum).[21]

text: In nematodes, the sperm cells are amoeboid and crawl, rather than swim, towards the egg cell.[22]

text: Non-motile sperm cells

text: Non-motile sperm cells called spermatia lack flagella and therefore cannot swim. Spermatia are produced in a spermatangium.[21]

text: Because spermatia cannot swim, they depend on their environment to carry them to the egg cell. Some red algae, such as Polysiphonia, produce non-motile spermatia that are spread by water currents after their release.[21] The spermatia of rust fungi are covered with a sticky substance. They are produced in flask-shaped structures containing nectar, which attract flies that transfer the spermatia to nearby hyphae for fertilization in a mechanism similar to insect pollination in flowering plants.[23]

text: Fungal spermatia (also called pycniospores, especially in the Uredinales) may be confused with conidia. Conidia are spores that germinate independently of fertilization, whereas spermatia are gametes that are required for fertilization. In some fungi, such as Neurospora crassa, spermatia are identical to microconidia as they can perform both functions of fertilization as well as giving rise to new organisms without fertilization.[24]

text: Sperm nuclei

text: In almost all embryophytes, including most gymnosperms and all angiosperms, the male gametophytes (pollen grains) are the primary mode of dispersal, for example via wind or insect pollination, eliminating the need for water to bridge the gap between male and female. Each pollen grain contains a spermatogenous (generative) cell. Once the pollen lands on the stigma of a receptive flower, it germinates and starts growing a pollen tube through the carpel. Before the tube reaches the ovule, the nucleus of the generative cell in the pollen grain divides and gives rise to two sperm nuclei, which are then discharged through the tube into the ovule for fertilization.[21]

text: In some protists, fertilization also involves sperm nuclei, rather than cells, migrating toward the egg cell through a fertilization tube. Oomycetes form sperm nuclei in a syncytical antheridium surrounding the egg cells. The sperm nuclei reach the eggs through fertilization tubes, similar to the pollen tube mechanism in plants.[21]

text: Sperm centrioles

text: Most sperm cells have centrioles in the sperm neck.[25] Sperm of many animals has 2 centrioles known as the proximal centriole and distal centriole. Some animals like human have a single centriole known as the proximal centriole. Mice and rat have no sperm centrioles. The fruit fly Drosophila melanogaster has a single centriole and an atypical centriole named the Proximal Centriole-Like (PCL).[26]

text: Sperm tail formation

text: The sperm tail is a specialized type of cilium (aka flagella). In many animals the sperm tail is formed in a unique way, which is named Cytosolic ciliogenesis, since all or part of axoneme of the sperm tail is formed in the cytoplasm or get exposed to the cytoplasm.[27]


document_title: Equilateral triangle

question_text: how many lines of symmetry are there in a equilateral triangle

text: Equilateral triangle

text: Principal properties[edit]

text: Denoting the common length of the sides of the equilateral triangle as a, we can determine using the Pythagorean theorem that:

text:
The area is

A
=

3

4

a

2

{\displaystyle A={\frac {\sqrt {3}}{4}}a^{2}}

The perimeter is

p
=
3
a

{\displaystyle p=3a\,\!}

The radius of the circumscribed circle is

R
=

a

3

{\displaystyle R={\frac {a}{\sqrt {3}}}}

The radius of the inscribed circle is

r
=

3

6

a

{\displaystyle r={\frac {\sqrt {3}}{6}}a}

 or

r
=

R
2

{\displaystyle r={\frac {R}{2}}}

The geometric center of the triangle is the center of the circumscribed and inscribed circles
And the altitude (height) from any side is

h
=

3

2

a

{\displaystyle h={\frac {\sqrt {3}}{2}}a}

.

tag: ul

text: Denoting the radius of the circumscribed circle as R, we can determine using trigonometry that:

text:
The area of the triangle is

A

=

3

3

4

R

2

{\displaystyle \mathrm {A} ={\frac {3{\sqrt {3}}}{4}}R^{2}}

text: Many of these quantities have simple relationships to the altitude ("h") of each vertex from the opposite side:

text:
The area is

A
=

h

2

3

{\displaystyle A={\frac {h^{2}}{\sqrt {3}}}}

The height of the center from each side, or apothem, is

h
3

{\displaystyle {\frac {h}{3}}}

The radius of the circle circumscribing the three vertices is

R
=

2
h

3

{\displaystyle R={\frac {2h}{3}}}

The radius of the inscribed circle is

r
=

h
3

{\displaystyle r={\frac {h}{3}}}

text: In an equilateral triangle, the altitudes, the angle bisectors, the perpendicular bisectors and the medians to each side coincide.

text: Characterizations[edit]

text: A triangle ABC that has the sides a, b, c, semiperimeter s, area T, exradii ra, rb, rc (tangent to a, b, c respectively), and where R and r are the radii of the circumcircle and incircle respectively, is equilateral if and only if any one of the statements in the following nine categories is true. Thus these are properties that are unique to equilateral triangles, and knowing that any one of them is true directly implies that we have an equilateral triangle.

text: Sides[edit]

text:
a
=
b
=
c

{\displaystyle \displaystyle a=b=c}

1
a

+

1
b

+

1
c

=

25
R
r
−
2

r

2

4
R
r

{\displaystyle \displaystyle {\frac {1}{a}}+{\frac {1}{b}}+{\frac {1}{c}}={\frac {\sqrt {25Rr-2r^{2}}}{4Rr}}}

 [1]

text: Semiperimeter[edit]

text:
s
=
2
R
+
(
3

3

−
4
)
r

(Blundon)

{\displaystyle \displaystyle s=2R+(3{\sqrt {3}}-4)r\quad {\text{(Blundon)}}}

[2]

s

2

=
3

r

2

+
12
R
r

{\displaystyle \displaystyle s^{2}=3r^{2}+12Rr}

 [3]

s

2

=
3

3

T

{\displaystyle \displaystyle s^{2}=3{\sqrt {3}}T}

 [4]

s
=
3

3

r

{\displaystyle \displaystyle s=3{\sqrt {3}}r}

s
=

3

3

2

R

{\displaystyle \displaystyle s={\frac {3{\sqrt {3}}}{2}}R}

text: Angles[edit]

text:
A
=
B
=
C
=

60

∘

{\displaystyle \displaystyle A=B=C=60^{\circ }}

cos

A

+
cos

B

+
cos

C

=

3
2

{\displaystyle \displaystyle \cos {A}+\cos {B}+\cos {C}={\frac {3}{2}}}

sin

A
2

sin

B
2

sin

C
2

=

1
8

{\displaystyle \displaystyle \sin {\frac {A}{2}}\sin {\frac {B}{2}}\sin {\frac {C}{2}}={\frac {1}{8}}}

 [5]

text: Area[edit]

text:
T
=

a

2

+

b

2

+

c

2

4

3

{\displaystyle \displaystyle T={\frac {a^{2}+b^{2}+c^{2}}{4{\sqrt {3}}}}\quad }

 (Weitzenböck) [6]

T
=

3

4

(
a
b
c

)

2
3

{\displaystyle \displaystyle T={\frac {\sqrt {3}}{4}}(abc)^{^{\frac {2}{3}}}}

 [4]

text: Circumradius, inradius and exradii[edit]

text:
R
=
2
r

(Chapple-Euler)

{\displaystyle \displaystyle R=2r\quad {\text{(Chapple-Euler)}}}

[7]

9

R

2

=

a

2

+

b

2

+

c

2

{\displaystyle \displaystyle 9R^{2}=a^{2}+b^{2}+c^{2}}

 [7]

r
=

r

a

+

r

b

+

r

c

9

{\displaystyle \displaystyle r={\frac {r_{a}+r_{b}+r_{c}}{9}}}

 [5]

r

a

=

r

b

=

r

c

{\displaystyle \displaystyle r_{a}=r_{b}=r_{c}}

text: Equal cevians[edit]

text: Three kinds of cevians are equal for (and only for) equilateral triangles:[8]

text:
The three altitudes have equal lengths.
The three medians have equal lengths.
The three angle bisectors have equal lengths.

text: Coincident triangle centers[edit]

text: Every triangle center of an equilateral triangle coincides with its centroid, which implies that the equilateral triangle is the only triangle with no Euler line connecting some of the centers. For some pairs of triangle centers, the fact that they coincide is enough to ensure that the triangle is equilateral. In particular:

text:
A triangle is equilateral if any two of the circumcenter, incenter, centroid, or orthocenter coincide.[9]:p.37
It is also equilateral if its circumcenter coincides with the Nagel point, or if its incenter coincides with its nine-point center.[7]

text: Six triangles formed by partitioning by the medians[edit]

text: For any triangle, the three medians partition the triangle into six smaller triangles.

text:
A triangle is equilateral if and only if any three of the smaller triangles have either the same perimeter or the same inradius.[10]:Theorem 1
A triangle is equilateral if and only if the circumcenters of any three of the smaller triangles have the same distance from the centroid.[10]:Corollary 7

text: Points in the plane[edit]

text: A triangle is equilateral if and only if, for every point P in the plane, with distances p, q, and r to the triangle's sides and distances x, y, and z to its vertices,[11]:p.178,#235.4

text: Notable theorems[edit]

text: Morley's trisector theorem states that, in any triangle, the three points of intersection of the adjacent angle trisectors form an equilateral triangle.

text: Napoleon's theorem states that, if equilateral triangles are constructed on the sides of any triangle, either all outward, or all inward, the centers of those equilateral triangles themselves form an equilateral triangle.

text: A version of the isoperimetric inequality for triangles states that the triangle of greatest area among all those with a given perimeter is equilateral.[12]

text: Viviani's theorem states that, for any interior point P in an equilateral triangle with distances d, e, and f from the sides and altitude h,

text: independent of the location of P.[13]

text: Pompeiu's theorem states that, if P is an arbitrary point in an equilateral triangle ABC, then there exists a triangle with sides of lengths PA, PB, and PC. That is, PA, PB, and PC satisfy the triangle inequality that any two of them sum to at least as great as the third.

text: Other properties[edit]

text: By Euler's inequality, the equilateral triangle has the smallest ratio R/r of the circumradius to the inradius of any triangle: specifically, R/r = 2.[14]:p.198

text: The triangle of largest area of all those inscribed in a given circle is equilateral; and the triangle of smallest area of all those circumscribed around a given circle is equilateral.[15]

text:
The ratio of the area of the incircle to the area of an equilateral triangle,

π

3

3

{\displaystyle {\frac {\pi }{3{\sqrt {3}}}}}

, is larger than that of any non-equilateral triangle.[16]:Theorem 4.1

text:
The ratio of the area to the square of the perimeter of an equilateral triangle,

1

12

3

,

{\displaystyle {\frac {1}{12{\sqrt {3}}}},}

 is larger than that for any other triangle.[12]

text: If a segment splits an equilateral triangle into two regions with equal perimeters and with areas A1 and A2 , then[11]:p.151,#J26

text:
If a triangle is placed in the complex plane with complex vertices z1, z2, and z3, then for either non-real cube root

ω

{\displaystyle \omega }

 of 1 the triangle is equilateral if and only if[17]:Lemma 2

text: Given a point P in the interior of an equilateral triangle, the ratio of the sum of its distances from the vertices to the sum of its distances from the sides is greater than or equal to 2, equality holding when P is the centroid. In no other triangle is there a point for which this ratio is as small as 2.[18] This is the Erdős–Mordell inequality; a stronger variant of it is Barrow's inequality, which replaces the perpendicular distances to the sides with the distances from P to the points where the angle bisectors of ∠APB, ∠BPC, and ∠CPA cross the sides (A, B, and C being the vertices).

text: For any point P in the plane, with distances p, q, and t from the vertices A, B, and C respectively,[19]

text: For any point P on the inscribed circle of an equilateral triangle, with distances p, q, and t from the vertices,[19]

text: and

text: For any point P on the minor arc BC of the circumcircle, with distances p, q, and t from A, B, and C respectively,[13]:170[19]

text: and

text: moreover, if point D on side BC divides PA into segments PD and DA with DA having length z and PD having length y, then[13]:172

text:
which also equals

t

3

−

q

3

t

2

−

q

2

{\displaystyle {\tfrac {t^{3}-q^{3}}{t^{2}-q^{2}}}}

 if t ≠ q; and

text: which is the optic equation.

text: There are numerous triangle inequalities that hold with equality if and only if the triangle is equilateral.

text: An equilateral triangle is the most symmetrical triangle, having 3 lines of reflection and rotational symmetry of order 3 about its center. Its symmetry group is the dihedral group of order 6 D3.

text: Equilateral triangles are the only triangles whose Steiner inellipse is a circle (specifically, it is the incircle).

text: The integer-sided equilateral triangle is the only triangle with integer sides and three rational angles as measured in degrees.[20]

text: Equilateral triangles are found in many other geometric constructs. The intersection of circles whose centers are a radius width apart is a pair of equilateral arches, each of which can be inscribed with an equilateral triangle. They form faces of regular and uniform polyhedra. Three of the five Platonic solids are composed of equilateral triangles. In particular, the regular tetrahedron has four equilateral triangles for faces and can be considered the three-dimensional analogue of the shape. The plane can be tiled using equilateral triangles giving the triangular tiling.

text: Geometric construction[edit]

text: An equilateral triangle is easily constructed using a compass and straightedge, as 3 is a Fermat prime. Draw a straight line, and place the point of the compass on one end of the line, and swing an arc from that point to the other point of the line segment. Repeat with the other side of the line. Finally, connect the point where the two arcs intersect with each end of the line segment

text: An alternative method is to draw a circle with radius r, place the point of the compass on the circle and draw another circle with the same radius. The two circles will intersect in two points. An equilateral triangle can be constructed by taking the two centers of the circles and either of the points of intersection.

text: In both methods a by-product is the formation of vesica piscis.

text: The proof that the resulting figure is an equilateral triangle is the first proposition in Book I of Euclid's Elements.

text: Derivation of area formula[edit]

text:
The area formula

A
=

3

4

a

2

{\displaystyle A={\frac {\sqrt {3}}{4}}a^{2}}

 in terms of side length a can be derived directly using the Pythagorean theorem or using trigonometry.

text: Using the Pythagorean theorem[edit]

text: The area of a triangle is half of one side a times the height h from that side:

text: The legs of either right triangle formed by an altitude of the equilateral triangle are half of the base a, and the hypotenuse is the side a of the equilateral triangle. The height of an equilateral triangle can be found using the Pythagorean theorem

text: so that

text: Substituting h into the area formula (1/2)ah gives the area formula for the equilateral triangle:

text: Using trigonometry[edit]

text: Using trigonometry, the area of a triangle with any two sides a and b, and an angle C between them is

text: Each angle of an equilateral triangle is 60°, so

text:
The sine of 60° is

3

2

{\displaystyle {\tfrac {\sqrt {3}}{2}}}

. Thus

text: since all sides of an equilateral triangle are equal.

text: In culture and society[edit]

text: Equilateral triangles have frequently appeared in man made constructions:

text:
Some archaeological sites have equilateral triangles as part of their construction, for example Lepenski Vir in Serbia.
The shape also occurs in modern architecture such as Randhurst Mall and the Jefferson National Expansion Memorial.
The Flag of Nicaragua, the Flag of the Philippines, the Seal of the President of the Philippines, and the Flag of Junqueirópolis contain equilateral triangles.
It is a shape of a variety of road signs, including the Yield sign.
The fraternity Tau Kappa Epsilon uses the equilateral triangle as its primary symbol.