document_title: Hell's Kitchen (U.S. season 10)

question_text: who did christina beat in hell's kitchen

question_tokens: who did christina beat in hell 's kitchen

root

text: Hell's Kitchen (U.S. season 10)

text: Production and development[edit]

text: This season saw an alteration to the show's format, with many episodes now being two-parters, depicting the team challenge and reward/punishment one night, followed by service and elimination the following night. This season is also the first (and currently only) season in Hell's Kitchen history in which all chefs were eliminated normally. In other words, no chef was eliminated either despite being on the winning team, without being nominated (with the exception of Dana and Barbie during the final selection), during dinner service, had to withdraw for medical reasons, or walked out on their own terms. This is also the first & only season where one challenge produced no winner and both teams faced punishment.

tag: p

text: Opening sequence[edit]

text: The opening sequence of Season 10 began with the iconic "Welcome to Fabulous Las Vegas" sign which morphed into "Welcome to Fabulous Hell's Kitchen". This is followed by a magic show-style opening featuring the chefs doing various stunts and tricks with Ramsay magically appearing at the end.

text: Chefs[edit]

text: 18 chefs competed in season 10. Full names per official site.[1]

text:
Contestant

Age

Occupation

Hometown

Result

Christina Wilson[2]

32

Chef de Cuisine

Philadelphia, Pennsylvania

Winner

Justin Antiorio

29

Sous Chef

Lyndhurst, New Jersey

Runner-Up

Dana Cohen[a][3]

27

Chef Instructor

River Vale, New Jersey

Eliminated before Finals

Barbra "Barbie" Marshall[b][2]

34

Catering Chef

Philadelphia, Pennsylvania

Eliminated before Finals

Clemenza Caserta

41

Executive Chef

Long Island, New York

Eliminated after Fourteenth Service

Robyn Almodovar[c]

31

Executive Sous Chef

Hollywood, Florida

Eliminated after Thirteenth Service

Brian Merel

31

Personal Chef

Chicago, Illinois

Eliminated before Black Jackets after Twelfth Service

Kimberly "Kimmie" Willis-Davenport[4]

27

Personal Chef

Memphis, Tennessee

Eliminated after Eleventh Service

Tiffany Johnson

30

Sous Chef

Warren, Vermont

Eliminated after Tenth Service

Royce Wagner

29

Sous Chef

Fort Lauderdale, Florida

Eliminated after Ninth Service

Patrick Cassata

40

Executive Chef

Lombard, Illinois

Eliminated after Eighth Service

Roshni Gurnani

28

Executive Chef

Boston, Massachusetts

Eliminated after Seventh Service

Guy Vaknin

28

Executive Catering Chef

New York, New York

Eliminated after Sixth Service

Danielle Rimmer

27

Saucier

Bayonne, New Jersey

Eliminated after Fifth Service

Donald "Don" Savage

44

Cafeteria Chef

Houston, Texas

Eliminated after Fourth Service

Briana Swanson

32

Personal Chef

New York, New York

Eliminated after Third Service

Christopher "Chris" Carrero

33

Executive Chef

Queens, New York

Eliminated after Second Service

Tavon Hubbard

22

Executive Chef

Washington, D.C.

Eliminated after First Service

tag: table

text:
Jump up ^ Chef returned to Hells Kitchen again on Season 17.

Jump up ^ Chef returned to Hells Kitchen again on Season 17.

Jump up ^ Chef returned to Hells Kitchen again on Season 17.

text: Contestant progress[edit]

text:
Original teams

First switch

Second switch

Individual

Finals

No.

Chef

1001

1002

1003

1004

1005/06

1006/07

1008

1009/10

1011

1012/13

1014

1015

1016

1017

1018

1019/20

1

Christina

WIN

LOSE

LOSE

LOSE

LOSE

WIN

WIN

LOSE

WIN

LOSE

LOSE

WIN

IN

IN

IN

WINNER

2

Justin

LOSE

LOSE

WIN

LOSE

LOSE

LOSE

LOSE

LOSE

LOSE

LOSE

LOSE

NOM[n 1]

IN

IN

IN

RUNNER-UP

3

Dana

WIN

LOSE

LOSE

LOSE

LOSE

WIN

WIN

LOSE

WIN

LOSE

LOSE

WIN

IN

IN

OUT

4

Barbie

BoB

NOM

NOM

LOSE

NOM

WIN

WIN

LOSE

WIN

NOM

LOSE

WIN

IN

NOM[n 1]

OUT

5

Clemenza

LOSE

LOSE

WIN

LOSE

LOSE

NOM

NOM[n 2]

LOSE

NOM

NOM

LOSE

NOM[n 1]

NOM

OUT[n 1]

6

Robyn

WIN

LOSE

LOSE

LOSE

LOSE

WIN

WIN

NOM

LOSE

NOM

NOM

NOM

OUT

7

Brian

LOSE

LOSE

WIN

NOM

LOSE

LOSE

NOM[n 2]

LOSE

LOSE

LOSE

LOSE

OUT[n 1]

8

Kimmie

WIN

LOSE

LOSE

LOSE

LOSE

WIN

WIN

LOSE

WIN

LOSE

OUT

9

Tiffany

WIN

LOSE

LOSE

LOSE

LOSE

WIN

WIN

NOM

WIN

OUT

10

Royce

NOM[n 1]

NOM

WIN

LOSE

LOSE

LOSE

LOSE

NOM

OUT

11

Patrick

LOSE

LOSE

WIN

LOSE

NOM

LOSE

NOM[n 1]

OUT

12

Roshni

WIN

NOM

NOM[n 1]

NOM

LOSE

BoW

OUT[n 1]

13

Guy

LOSE

BoW

WIN

LOSE

NOM

OUT

14

Danielle

WIN

LOSE

LOSE

NOM

OUT

15

Don

NOM[n 2]

LOSE

WIN

OUT

16

Briana

WIN

LOSE

OUT

17

Chris

LOSE

OUT

18

Tavon

OUT

text:
Keywords
WIN = Won the dinner service
LOSE = Lost the dinner service
BoB = Best of the Best, usually exempt from nomination
BoW = Best of the Worst, sometimes exempt from nomination
IN = not nominated for elimination
NOM = nominated for elimination
OUT = eliminated
LEFT = withdrew from competition

Color key
     Chef was eliminated after nomination
     Chef was eliminated without nomination
     Chef was eliminated during service
     Chef withdrew from the competition
     Chef was retained after nomination
     The winner of Hell's Kitchen
     The runner-up of Hell's Kitchen

text:
^ Jump up to: a b c d e f g h i Chef was nominated by Ramsay

^ Jump up to: a b c Although nominated, chef was not called down by Ramsay

text: Episodes[edit]

text: Each episode consists of a challenge with a reward, a service and an elimination.

text:
No.overallNo. inseasonTitleOriginal air dateUS viewers(millions)1251"18 Chefs Compete"June 4, 2012 (2012-06-04)5.46[5]
In this episode, 20 initial chefs were transported to Hell's Kitchen in a police-escorted motorcade, where sous chef Scott greeted them and explained he shaved his head to prove his dedication to Chef Ramsay, as did sous chef Andi. He called for volunteers to shave their heads; two of the "chefs" then turned out to be Scott's friends instead and got their heads shaved. Scott then called out actual contestant Danielle and was about to shave her head before Ramsay stopped him. It was later revealed that Andi was wearing a bald cap.
Team challenge: Each chef created their signature dish; men (blue team) competed against women (red team). Robyn's sea bass scored over Don's southwestern saltimbocca, neither Tiffany's Lamb Schnitzel nor Guy's pan-seared bass scored a point (Guy even told Ramsay not to try his dish as he burned his sauce), Roshni's lamb and Royce's grouper both scored points, Justin's dish scored over Danielle's, neither Kimmie's Fisherman's Trio nor Brian's dessert scored a point, neither Barbie's nor Chris' dish scored a point, Briana's and Patrick's dish both scored a point and Dana's pan-seared scallops scored over Tavon's shrimp scallops and crab. Lastly, Christina's pork chop scored over Clemenza's veal chop, giving the women a 5-3 win.
Reward/punishment: The women were treated to a steak meal with two Hell's Kitchen winners Rahman "Rock" Harper from Season 3 and Dave Levey from Season 6 while the men were forced to clean both kitchens.
Service: Leigh Bodden was a guest for opening night. In the red kitchen, Roshni was kicked out after undercooking and overcooking scallops, and although Barbie led the women to getting appetizers out, Christina's Wellingtons came out raw. In the blue kitchen, Tavon served raw pigeon, butchered the entire team's supply of scallops, and laughed after being scolded by Ramsay, getting him kicked out, while Royce had trouble finding anchovies for salads and was also kicked out for serving undercooked spaghetti against Clemenza's advice. Don did little, annoying his teammates, and the rest of the team was kicked out after Chris served an onion tart with raw pastry. After Christina still struggled on Wellingtons, Ramsay shut the red kitchen down. Though no entrées were served, the red team was named winners for at least serving all their appetizers; the blue team was told to nominate two for elimination.
Elimination: Tavon and Don were nominated. However, Ramsay overruled Don's nomination and nominated Royce. In the end, Tavon was eliminated for failing to live up to his executive chef position as well as being the worst performer of the night.

Ramsay's comment: "Tavon may have been an executive chef at 22, but he did little to impress me in his short stay in Hell's Kitchen."
1262"17 Chefs Compete"June 5, 2012 (2012-06-05)4.87
A rap group wakens the chefs inside the dorms.
Team challenge: The chefs removed 125 scallops from a large mound of ice and seaweed before cooking them to Ramsay's standards; the first team to make six plates of five scallops would win. The women won mainly thanks to Barbie and Tiffany, preparing six plates to the men's two.
Reward/punishment: The women went on a yacht cruise for a day on Santa Catalina Island, and went ziplining, (where Roshni completely stalled on the line). The men cleaned and prepped the kitchens and dining room for service, as well as drink smoothies made from rejected scallops.
Service: The service was deemed "Redemption Night", with Ramsay specifically wanting flawless scallops from both kitchens. Brian and Christina served shrimp scampi appetizer tableside. In the blue kitchen, Don served a burnt and also raw pizza, Brian served raw and also overcooked shrimp, Chris needed his teammates' help with scallops and served raw opah and Royce struggled on garnish. For the women, Robyn and Barbie did not work together well and served undercooked food. Barbie continually argued with her teammates and struggled on fish before Ramsay kicked the women out. After discovering an overcooked steak in the blue kitchen, Ramsay kicked the men out as well; Ramsay named both teams losers.
Elimination: The women nominated Barbie and Roshni while the men nominated Chris and Royce. Ramsay eliminated Chris for his awful performance on fish and for admitting he was "frazzled" during service.

Ramsay's comment: "I'm sure that Chris prays that he never sees another scallop. And after tonight, I pray I don't see any more of him."
1273"16 Chefs Compete"June 11, 2012 (2012-06-11)6.25[6]
Team challenge: Both teams had to cook a meal for 60 immigrants who had just become U.S. citizens. Barbie attempted to cook pizzas too early, while Clemenza undercooked his. The women won  their third challenge win in a row.[note 1]
Reward/punishment: The women were rewarded with a safari trip in San Diego. The men were sent to do hard labor at the Ballona Wetlands. Prior to service, Ramsay had season 1 runner-up Ralph Pagano, Royce's boss, give Royce a pep talk.
Service: A group of Marines were guests for this service. Don and Tiffany were assigned as servers, but Don's poor writing and bad spelling slowed the blue team down. Royce had a near-perfect performance on appetizers, but Clemenza struggled on meat, running out of Beef Wellingtons, though he recovered on steaks. Dana put too much sauce on spaghetti, while Briana and Barbie undercooked scallops. With Christina's help, the women served appetizers, but on entrees, Briana served cod missing half a portion. Kimmie started well, but undercooked Wellingtons, while Roshni forgot an order of dumplings and then served them undercooked. After Briana overcooked cod, Ramsay threw the red team out. The men were named clear winners and Ramsay praised Royce. Ramsay berated the women, but did praise Christina.
Elimination: Briana and Barbie were nominated. Ramsay also nominated Roshni but eliminated Briana for her lack of fightback.

Ramsay's comment: "Tonight, Briana had a battle with the cod, and the cod won. And that's why her time in Hell's Kitchen was a short one."
1284"15 Chefs Compete"June 12, 2012 (2012-06-12)5.32[7]
Ramsay woke the chefs early and took them to a lamb pen at a local farm.
Team challenge: Each chef retrieved as many ingredients off animals as possible, with the collars and paint indicators of each ingredient. They then split into pairs to create 4 different lamb dishes; as the blue team had one less member, Patrick worked on his own. Tiffany/Danielle and Clemenza/Don both earned a point on lamb chop, Roshni and Kimmie's ground lamb earned a point over Patrick's and Justin and Guy's lamb chop earned a point over Barbie and Robyn's. Lastly, Royce and Brian's lamb steak earned a point over Christina's and Dana's, giving the men their first challenge win.
Reward/punishment: The men celebrate their first challenge win were with a day at the horse races. The women had to wash paint off the sheep in addition to cleaning and prepping both kitchens. Their day gets worse when they ate lamb testicles for lunch.
Service: In the red kitchen, Danielle undercooked appetizers and was thrown out, while Roshni struggled on Beef Wellingtons and was also thrown out. For the men, Brian ran out of cod before being thrown out for calling Ramsay "baby". Ramsay then threw Don out for overcooking steak, followed by Robyn and Danielle for communication issues and Justin and Royce for both cooking bass for the same table. Service was completed, but both teams were named losers.
Elimination:The men nominated Don and Brian while the women nominated Roshni and Danielle. Ramsay eliminated Don for his lack of improvement over four services.
Team change: Ramsay then transferred Roshni to the men.

Ramsay's comment: "Everyone in Hell's Kitchen starts at the bottom. Unfortunately, Don stayed there."
1295"14 Chefs Compete"June 18, 2012 (2012-06-18)5.65[8]
Team challenge: Sous chef Scott brought a large donkey piñata to the teams and Ramsay explained that the piñata would pour out balls with ingredients labelled on them. Each chef had 25 ingredients to work on six different Mexican dishes, before each team selected five to be judged by Ramsay and two guest judges. The red team won 3-2, with Dana’s dish being noted as the best.
Reward/punishment: The red team went to one of the guest judge's gourmet restaurant for lunch and later an outdoor salsa dancing class. The blue team had to prep both kitchens, make handmade salsa for service and eat tripe for lunch.
Service: The service was Mexican night. The blue team started badly with Guy delivering undercooked tuna, but he recovered. On the red team, Barbie served incorrectly seasoned mussels and Kimmie baffled Ramsay by putting meat and fish on the same tray. Several chefs were kicked out; Guy and Patrick for communication issues, Danielle for serving raw pork twice, Justin and Clemenza after Justin served meat despite Clemenza's warning, Barbie for using a thermometer in chicken, Tiffany for serving burnt mashed potatoes and Royce for serving burnt chicken. The remaining chefs finished service, but Ramsay again named no winner.

Elimination: The blue team nominated Patrick and Guy while the red team nominated Barbie and Danielle. Ramsay sent Barbie back in line, but the episode then ended in a cliffhanger.
1306"13 Chefs Compete, Part 1"June 19, 2012 (2012-06-19)5.34[9]
Continued from the previous episode, Ramsay eliminated Danielle for her second consecutive awful service. Ramsay did not give a comment on Danielle's elimination and she did not receive a coat hook and burning picture scene.
Team challenge: Both teams prepared an appetizer and two entrées (seafood and poultry) for three fashion designer judges; David Meister, Amanda Che and Ina Soltani. Christina and Dana's appetizer scored over Brian and Justin's, and Roshni and Patrick's poultry dish scored over Barbie and Tiffany's. Clemenza, Royce and Guy's seafood dish then beat out Kimmie and Robyn's, giving the blue team the win.
Reward/punishment: The blue team was treated to a shopping spree in Malibu. The red team had to assemble the runway for Hell's Kitchen's first-ever fashion show.

Pre-service: Ramsay chose Kimmie and Royce to assist with plating dishes. Clemenza started cooking scallops before the show started and, upon questioning, Ramsay found out he cooked four servings as the episode ends with "To Be Continued" cliffhanger.
1317"13 Chefs Compete, Part 2"June 25, 2012 (2012-06-25)5.66[10]
Pre-service - continued: Despite Clemenza's mistake, Ramsay ordered Hell's Kitchen to be opened.
Service : The red team beat out the blue team on appetizers as Clemenza got overwhelmed with the number of scallop orders, but redeemed himself on entrées. Guy got distracted and was scolded, while Robyn ran out of beef, was scolded for asking Christina to get some from the blue kitchen and was eventually forced to apologize to the customers and offer them a different entree. Tiffany undercooked swordfish and then tried to blame it on Christina, while Guy undercooked beef and Royce struggled plating food. Both teams completed service, but Ramsay discovered a leftover tray of swordfish, resulting in an argument between Clemenza and Royce over who was responsible. The red team was named winners, with Kimmie being named best of the night.
Elimination: Clemenza and Guy were nominated. While the blue team all blamed Clemenza, Ramsay eliminated Guy for his lack of fight-back, but praised him for his hard work.

Ramsay's comment: "Guy's performance in Hell's Kitchen was extremely inconsistent. That is why I know he is not THE guy to run Gordon Ramsay Steak."
1328"12 Chefs Compete"June 26, 2012 (2012-06-26)5.51[11]
Team challenge: In front of each team were four domes and each dome contained six ingredients. Every five minutes, one dome became available for use. Each team member was told to take one ingredient from each dome that matches their protein and were judged by three Michelin-starred chefs, Michael Cimarusti, Anita Lo and Douglas Keane. The red team won 30-29 after Christina's lobster dish received three stars from Anita. Her dish was placed on the menu for dinner service.
Reward/punishment: The red team spent a day at a spa and a set of Demeyere cookware each. The blue team prepped both kitchens for service and cleaned the dorms.
Service: Tito Ortiz and Sugar Ray Leonard were seated at the chef's tables, with Robyn and Justin supervising them. The red team had little trouble except for Christina undercooking risotto and Tiffany having trouble on meat, including using a dirty knife to check a Wellington, but the team rebounded. In the blue kitchen, Clemenza served hard pasta, Brian served soupy risotto, although both rebounded however Roshni served raw and overcooked meat and Ramsay kicked the blue team out after Patrick served cold lobster twice. Ramsay had the red team complete their service.
Elimination: Brian and Clemenza were nominated. Ramsay, angry, overruled and nominated Roshni and Patrick. Ramsay eliminated Roshni for her irregular performances, but praised her for her big heart.

Ramsay's comment: "Roshni is a small lady with a big heart. Unfortunately, her performance tonight matched her stature."
1339"11 Chefs Compete Part 1"July 2, 2012 (2012-07-02)5.83[12]
Team challenge: A slot machine was spun and determined what type of ingredients and steak one member of each team had to cook in 30 minutes. Since Kimmie did not spin due to the women having an extra member, she got to choose which batch of ingredients she would cook with; she chose Robyn's, but Robyn's ribeye steak was chosen over Kimmie's. Justin's filet mignon scored over Tiffany's, Christina's hangar steak scored over Royce's, neither Dana's or Patrick's flat iron steak scored a point and both Barbie's and Brian's New York strips scored a point. Clemenza's ribeye steak then scored over Robyn's, giving the men a 3-2 win. Ramsay told the women they should have chosen Kimmie's steak, which he preferred.
Reward/punishment: The blue were rewarded with a shopping spree for kitchenware and utensils, followed by lunch at Comme Ça. The red team prepped the beef for service.

Kimmie's injury: Dinner service's is a combination of steakhouse and family night. Shortly before service, Kimmie burned her left hand and arm picking up a pan with hot grease; while she was medically treated, she argued with Robyn. The episode then ended in another "To be continued" cliffhanger.
13410"11 Chefs Compete Part 2"July 3, 2012 (2012-07-03)5.07[13]
Kimmie's injury - continued: Despite being advised by the medic not to take part in service, Kimmie decided to, which led to her team (bar Robyn) praising her dedication.
Service: Tiffany burned pizzas for the kids and served inconsistent blinis for smoked salmon, but Barbie took over and served perfect appetizers, earning praise from Ramsay. Kimmie and Robyn continued to argue and failed to get entrées out due to disagreeing over times. On the blue team, Patrick and Royce were thrown out for serving raw meat and Brian was scolded for acting goofy. Ramsay called Clemenza, Brian and Justin to assist the red team, but the fighting among the women continued and Ramsay threw them out after Robyn served raw steak. Although the men finished both teams' services, Ramsay named both teams losers.
Elimination: The blue team nominated Patrick and Royce while the red team nominated Tiffany and Robyn. Ramsay eliminated Patrick for failing to live up to his Executive Chef position and inconsistent performances.
Team change: Ramsay then accepted Robyn's request to be transferred to the men's team, though he warned her to stop blaming others for her mistakes.

Ramsay's comment: "Patrick talked a good game, but he couldn't back it up with his cooking so it was time for him to leave Hell's Kitchen."
13511"10 Chefs Compete"July 9, 2012 (2012-07-09)6.01[14]
Team challenge: Each team member rolled a 12-sided dice, with each face having a letter, and had to think of a food item beginning with that letter, after which each team had to produce one dish using all the ingredients named.[note 2] The blue team narrowly won after the red team's brussel sprouts were undercooked.
Reward/punishment: The blue team head to Southwest Airlines for a flight to Las Vegas, where they spent an entire evening at the Paris Las Vegas. The red team spent all night barbecuing a pig to make pulled pork, with an alarm sounding every hour.
Service: Chef's tables were featured in this service. The blue team cooked for two American Idol contestants which include Season 9 winner Lee DeWyze and Season 10 finalist Haley Reinhart while the red team cooked for David Beckham and his son Brooklyn. Tiffany mistook cod for sea bass twice, but Barbie had an excellent performance on meat. The blue team struggled with Royce on meat, Clemenza on fish and Brian on flatbread, so Ramsay took all the male blue team members aside for a time out. After the red team finished service, Ramsay had them help the blue team. The red team were named winners and Barbie was named best of the night. Ramsay criticized the blue team, but did praise Robyn.
Elimination: Royce and Clemenza were nominated. Ramsay had them both remove their jackets and eliminated Royce for failing to live up to his abilities to his mentor before giving Clemenza a clean jacket.

Ramsay's comment: "Royce came in promising a Rolls-Royce service. But instead, his service was like a broken-down car. Time to send Royce to the junkyard."
13612"9 Chefs Compete Part 1"July 16, 2012 (2012-07-16)6.33[15]
Two chefs from each team competed against competitive eater Joey Chestnut in a chicken wing contest; Brian/Justin and Barbie/Tiffany had 60 wings to eat between them, while Chestnut had 60 to himself. The first to finish won $500 in cash; Chestnut won.
Team challenge: The annual "blind taste test" then took place; since the red team had an extra member, Kimmie sat out. Brian identified three ingredients compared to Christina's two, Barbie scored one while Robyn failed to get any and Tiffany scored one while Clemenza also failed to get any. Lastly, Dana scored two, but Justin became the first chef in Hell's Kitchen history to get a perfect score of four, giving the blue team a 7-6 win.
Reward/punishment: The blue team spent a day at the Raging Waters water park in San Dimas. The red team spent the day taking in deliveries, grinding peppercorns with a mortar and pestle, changing the oil in the fryers and peeling potatoes. Durning the punishment, Kimmie got into a fight with Barbie about how little work she was doing and Barbie insulted Kimmie's Weight.

Pre-service: The teams received an iPad video message from Ramsay, instructing them to create their own menu, consisting of three appetizers, three entrées and three desserts. Barbie prepped at a slow pace, annoying her teammates, the first batch of Kimmie's barbecue sauce tasted awful, forcing Christina to help her, and Dana helped Tiffany with potatoes since they were crunchy, while Clemenza stepped out of prep to clean his jacket. Ramsay had issues with the red team's appetizers, but had positive comments about their entrées. By contrast, Ramsay did not like any of the blue team's dishes, eventually finding several bones in Clemenza's quail dish, leading him to threaten Clemenza with elimination before service. The episode then ended with another "To be continued" cliffhanger.
13713"9 Chefs Compete Part 2"July 17, 2012 (2012-07-17)6.02[16]
Pre-service - continued: Ramsay warned the blue team to step up their game.
Service: The customers submitted comment cards based on which team's dishes they preferred. The blue team ran out of scallops, leading to Robyn suggesting an alternate to the diners, Brian struggled to cook bass, Robyn faced problems with Justin's complicated dish, Justin overcooked prime steak and Clemenza lied to Ramsay after forgetting a sea bass. After numerous dishes were rejected for being overcooked and undercooked, Ramsay kicked the blue team out, despite only having one ticket left. For the red team, Christina got overwhelmed on flatbreads, Kimmie overcooked ribeye steak, Dana served raw lobster and Tiffany cooked garnish in a dirty pan. Tiffany got stalled on potatoes, and when she argued with sous chef Andi, Andi kicked her out. Despite the red team finishing service, Ramsay tore up the customers' comment cards and named both teams losers, describing tonight's service as their worst so far, and is disappointed that everyone made mistakes on a menu they all created.
Elimination: The blue team nominated Robyn and Clemenza while the women nominated Tiffany and Barbie. Ramsay eliminated Tiffany for her lack of passion and leadership.

Ramsay's comment: "The most passionate I ever saw Tiffany was moments ago when she was already on her way out. That was just too late."
13814"8 Chefs Compete"July 23, 2012 (2012-07-23)6.46[18]
Team challenge: A southern gospel choir, the Southern Voices of Victory, serenaded the chefs with their rendition of This Little Light of Mine before the challenge. The teams split into pairs and one from each team cooked a modernized version of a Southern entrée and side item, each revealed on a fan held by a choir member that the chefs chose. They then had 30 minutes to cook the items and were judged by Ramsay and Epicurious editor Tanya Steel. The red team won 3-1, with Dana's dish being judged best, leading for her dish to be featured on Epicurious.[17]
Reward/punishment: The red team were featured in a photo shoot for Epicurious followed by a trip for lunch at The Four Seasons in Beverly Hills. The blue team prepped for service, which involved baking biscuits and churning butter from scratch.
Dinner service: Service featured a special menu of Southern cuisine. There were only minor faults on appetizers in both kitchens, but on entrées, Kimmie undercooked and overcooked catfish, Barbie under-seasoned garnish, Robyn undercooked chicken and Brian overcooked fish. When Brian gave Ramsay a snide answer, Ramsay kicked him out. After prompting by maître d' James, Brian returned and fought back, but the numerous mistakes continued and Ramsay threw both teams out, leaving him and the sous chefs to complete service. Furious, Ramsay ordered both teams to nominate one chef for elimination.
Elimination: The red team nominated Kimmie and the blue team nominated Robyn. Ramsay eliminated Kimmie for not living up to her expertise on southern cooking, but praised her for her passion and drive.

Ramsay's comment: "As a woman from Memphis, tonight's Southern cuisine menu should've been an easy walk in the park for Kimmie. But it turned out to be a difficult uphill battle, and that is why it was her time to go."
13915"7 Chefs Compete"July 24, 2012 (2012-07-24)6.23[19]
Team challenge: The chefs had to prepare three dishes from the regular Hell's Kitchen menu in a tag-team race. Ramsay then judged the dishes on completeness, taste and appearance. However, all the dishes from both teams were rejected by Ramsay, making both teams losers and marking the first time in the history of Hell's Kitchen that neither team won a challenge.
Punishment: The reward would have been a day at the beach in Santa Monica with lunch and a helicopter tour. Instead, both teams were forced to detail the SUVs, clean the restaurant and prepare for that night's service.
Service: The red team did very well in service, their only problems being Christina cooking too much risotto and Dana needlessly cooking each piece of fish in a separate pan, but they finished well before the blue team, who failed to get entrées out, causing some of their tables to walk out. Clemenza had trouble putting out multiple appetizers at the same time and Robyn put all her garnishes in the oven and then tried to blame her team. Justin served old sea bass and Brian failed to serve meat at the right temperature, losing control soon after. Ramsay kicked Brian off and had Barbie take over. The red team were named clear winners and Christina, Dana and Barbie were given black jackets.[note 3]
Elimination: The blue team nominated Robyn, but could not choose between Brian and Clemenza, so Ramsay also nominated Brian, Clemenza and Justin. Clemenza and Justin were given black jackets before Robyn was given the final black jacket and Brian was eliminated for giving up easily in service and not having a more serious attitude.

Ramsay's comment: "Brian had a lot of energy and was a funny guy. But after tonight's performance, I wasn't laughing. And that's why he has to leave Hell's Kitchen."
14016"6 Chefs Compete"August 13, 2012 (2012-08-13)6.58[20]
Team challenge: The chefs were split into pairs (Barbie/Justin, Christina/Robyn and Clemenza/Dana) and had to taste Chef Lefebvre's and Chef Hatfield's dishes. This led to the actual "taste it, make it" challenge, in which the chefs had to distinguish the ingredients in Ramsay's dish and reproduce it in 30 minutes. Clemenza and Dana won.
Reward/punishment: Clemenza and Dana went to Silverwood Lake for a day of jet skiing and enjoying a gourmet picnic. The others cleaned the dining room, and polish glasses and silverware.
Service: The chefs competed against another team, composed of runners-up from previous seasons of Hell's Kitchen: Russell Kook II (season 8), Jay Santos (season 7), Kevin Cottle (season 6), Paula DaSilva (season 5), Bonnie Muirhead (season 3) and Virginia Dalbeck (season 2). The runner-up team had a virtually flawless service from start to finish, with Ramsay commenting how fast food was leaving the kitchen. Their only real mistake was Jay getting overwhelmed on fish, though even then, Kevin helped him get service back on track. For the black team, Robyn underdressed the caesar salads, and she and Clemenza cooked appetizers not on order. Dana failed to ask for help and control the fish station, Robyn was kicked out for talking back to Ramsay and Clemenza overcooked scallops. Ramsay told the black team their service was "not bad", but the returning chefs were deemed to have been far better, meaning one member of the black team would be eliminated.
Elimination: Robyn and Clemenza were nominated. Ramsay eliminated Robyn for her inconsistency and lack of teamwork, but praised her for her passion.

Ramsay's comment: "Making it to the black jackets was a dream come true for Robyn. But cooking against the runners-up was a reality check for her and for me."
14117"5 Chefs Compete"August 20, 2012 (2012-08-20)6.23[21]
Challenge: The chefs had to teach five Miss Teen USA winners, Kamie Crawford, Stevi Perry, Hilary Cruz, Katie Blair and Allie LaForce, how to cook a chicken parmesan dish; Barbie won.
Reward/punishment: Barbie was treated to a gourmet Italian lunch and kayaking in the Venice canals. In addition, she chose Justin to go with her. The others prepped for Italian service.
Dinner service: Before service, Sous Chef Scott caught Clemenza overtenderizing chicken. Barbie incorrectly cooked risotto numerous times, to a point where Ramsay threatened to throw her out if she messed up again, Dana burnt filets and Clemenza, despite producing perfect flatbreads, had a dirty workspace. Christina burned and under-seasoned sides, but recovered. Ramsay expressed disappointment with the performance and had the team nominate one for elimination.

Elimination: The team could not choose between Barbie and Clemenza, so Ramsay nominated both of them.[note 4] Ramsay eliminated Clemenza for his inconsistency and lack of organization, but commended him on his effort; Ramsay provided no comment on Clemenza's elimination and he did not receive a coat hook and burning picture scene. The final four found a champagne bottle from Ramsay, which included a congratulations note and a promised surprise the following night.
14218"4 Chefs Compete"August 27, 2012 (2012-08-27)6.87[22]
The chefs were treated to a visit from their loved-ones, Christina's mother and girlfriend, Dana's parents, Barbie's husband and children, and Justin's parents.
Challenge: The chefs were taken to a Bristol Farms supermarket, where they had 10 minutes to spend up to $15 on ingredients before having 30 minutes to cook their dish. Three judges, two restaurateurs and a critic for Bon Appétit magazine, priced the dishes, with the chef with the highest average price winning. Dana won with her panko-coated halibut, narrowly beating out Christina, while Barbie finished third and Justin last.
Reward/punishment: Dana visited the Manhattan Beach Post restaurant, where the chef helped her cook a dish and serve it to her parents. The others sort recyclable material from the garbage and prepped the kitchen for service.
Service: Paris Las Vegas president David Hoenemeyer was a guest for this service. The chefs took turns running the pass while having to spot acts of sabotage Ramsay and sous chefs Scott and Andi set up. Justin had a very strong start, spotting crab instead of lobster in a spaghetti, and only had trouble with Dana's poor attitude on fish. Dana was strong in leadership, but failed to notice that a risotto was seasoned with sugar instead of salt. Barbie kept addressing her orders to the diners instead of the chefs, but managed to catch mashed celeriac instead of mashed potatoes. Christina had a rough start when Dana kept getting her times wrong, but became more vocal and decisive, catching arugula instead of spinach.

Elimination: Ramsay announced that two chefs would advance to the final. After each chef gave a reason to stay, Ramsay eliminated Barbie, but praised her for her improvement, passion and hard work. The episode then ended in a "To Be Continued" cliffhanger as Ramsay prepared to name the two chefs advancing to the final.
14319"2 Chefs Compete"September 4, 2012 (2012-09-04)6.17[23]
Elimination - continued: Ramsay chose Christina and Justin to advance to the final, eliminating Dana, but Ramsay allowed Dana to keep her jacket.
Christina and Justin prepared a menu of four appetizers, four entrées and three desserts before Ramsay sent them on a private jet to Las Vegas, where they meet sous chefs Scott and Andi poolside at the Paris Las Vegas. They spent a day at a pool and had dinner with their loved ones. Later, they saw Penn & Teller perform, which featured Ramsay as part of a magic trick.
Challenge: Christina and Justin then had each one hour to cook five entrées, judged by five well-renowned chefs, including Wolfgang Puck. Christina won 3–2.
Reward: Christina was granted first pick in drafting a team using the eight chefs eliminated from the competition prior to the final.[note 5] Christina picked Dana, Patrick, Kimmie and Robyn, while Justin chose Barbie, Brian and Royce, and was left with Clemenza.

Christina and Justin then briefed their team on their menus, but Clemenza, upset over being picked last, began to walk out. The episode then ended in a "To Be Continued" cliffhanger.
14420"Winner Chosen"September 10, 2012 (2012-09-10)6.27[24]
Continued from the last episode, while Clemenza was less than enthused, he decided to take part. Christina and Justin held one final briefing the following morning, but Clemenza did not show up, causing Justin to encourage him. Ramsay gave each of the menu items a taste test, identifying dishes in need of tweaking, before starting Hell's Kitchen's 140th service.
Service: Both teams encountered problems. Clemenza burned the bruschetta, Royce served raw crab cakes and undercooked meat, and Barbie overcooked ribeye steak. After conferring, Justin served filet mignon as a substitute. On Christina's team, despite Christina distrusting Robyn, she put in a solid performance, while Dana struggled on fish. Near the end of service, an undercooked pork from Dana went to the pass for the red team, leading Ramsay to ask Christina to either serve it or restart the table. She decided to restart, a decision he approved of. Both teams completed service. Before he sends the finalists to the dorms, Ramsay named Tavon the winner of Hell's Kitchen as a joke.
Winner: After deliberating, Ramsay called Christina and Justin to his office and sent them to two doors; Christina's door opened, making her the tenth winner of Hell's Kitchen. Christina hung her portrait on the Wall of Fame and Justin took his defeat graciously.

Ramsay's comment: "Christina's passion and talent are undeniable. She's a strong leader who is totally at home in the kitchen. I know I'm not rolling the dice with her in Vegas because she is the real deal."

text: Notes[edit]

text:
Jump up ^ The men's loss meant they set a record for the worst start in Hell's Kitchen history, with five lost challenges/services out of five.

Jump up ^ Clemenza chose heirloom tomato, Justin chose daikon, Robyn chose dragonfruit, Brian chose edamame and Royce chose chicken. For the red team, Tiffany chose chicory, Barbie chose lamb, Kimmie chose turnips, Dana chose brussels sprouts and Christina chose truffles.

Jump up ^ The blue team set the worst competitive record of any blue team in the history of Hell's Kitchen dinner services. They were victorious only once in twelve services, losing five outright to the red team as well as suffering six joint losses.

Jump up ^ Clemenza's nomination count ties with Autumn Lewis of season 7 Sabrina Brimhall of season 8, Elise Wims in Season 9 and Scott Commings of Season 12.

Jump up ^ Tiffany did not return, so Patrick took her place as the last person eliminated prior to the top ten.


document_title: Eukaryotic transcription

question_text: in a eukaryotic cell which organelle is the site of trancription

text: Eukaryotic transcription

text: Overview[edit]

text: Transcription is the process of copying genetic information stored in a DNA strand into a transportable complementary strand of RNA.[1] Eukaryotic transcription takes place in the nucleus of the cell and proceeds in three sequential stages: initiation, elongation, and termination.[1] The transcriptional machinery that catalyzes this complex reaction has at its core three multi-subunit RNA polymerases. RNA polymerase I is responsible for transcribing RNA that codes for genes that become structural components of the ribosome. [1]

text: Protein coding genes are transcribed into messenger RNAs (mRNAs) that carry the information from DNA to the site of protein synthesis.[1] Although mRNAs possess great diversity, they are not the most abundant RNA species made in the cell. The so-called non-coding RNAs account for the large majority of the transcriptional output of a cell.[2] These non-coding RNAs perform a variety of important cellular functions.[2]

text: RNA polymerase[edit]

text: Eukaryotes have three nuclear RNA polymerases, each with distinct roles and properties[3][4]

text:
Name
Location
Product

RNA Polymerase I (Pol I, Pol A)
nucleolus
larger ribosomal RNA (rRNA) (28S, 18S, 5.8S)

RNA Polymerase II (Pol II, Pol B)
nucleus
messenger RNA (mRNA), most small nuclear RNAs (snRNAs), small interfering RNA (siRNAs) and microRNA (miRNA).

RNA Polymerase III (Pol III, Pol C)
nucleus (and possibly the nucleolus-nucleoplasm interface)
transfer RNA (tRNA), other small RNAs (including the small 5S ribosomal RNA (5s rRNA), snRNA U6, signal recognition particle RNA (SRP RNA) and other stable short RNAs

text: RNA polymerase I (Pol I) catalyses the transcription of all rRNA genes except 5S.[3][4] These rRNA genes are organised into a single transcriptional unit and are transcribed into a continuous transcript. This precursor is then processed into three rRNAs: 18S, 5.8S, and 28S. The transcription of rRNA genes takes place in a specialised structure of the nucleus called the nucleolus,[5] where the transcribed rRNAs are combined with proteins to form ribosomes.[6]

text: RNA polymerase II (Pol II) is responsible for the transcription of all mRNAs, some snRNAs, siRNAs, and all miRNAs.[3][4] Many Pol II transcripts exist transiently as single strand precursor RNAs (pre-RNAs) that are further processed to generate mature RNAs.[1] For example, precursor mRNAs (pre-mRNAs)are extensively processed before exiting into the cytoplasm through the nuclear pore for protein translation.

text: RNA polymerase III (Pol III) transcribes small non-coding RNAs, including tRNAs, 5S rRNA, U6 snRNA, SRP RNA, and other stable short RNAs such as ribonuclease P RNA.[7]

text: RNA Polymerases I, II, and III contain 14, 12, and 17 subunits, respectively.[8] All three eukaryotic polymerases have five core subunits that exhibit homology with the β, β’, αI, αII, and ω subunits of E. coli RNA polymerase. An identical ω-like subunit (RBP6) is used by all three eukaryotic polymerases, while the same α-like subunits are used by Pol I and III. The three eukaryotic polymerases share four other common subunits among themselves. The remaining subunits are unique to each RNA polymerase. The additional subunits found in Pol I and Pol III relative to Pol II, are homologous to Pol II transcription factors.[8]

text: Crystal structures of RNA polymerases I[9] and II [10] provide an opportunity to understand the interactions among the subunits and the molecular mechanism of eukaryotic transcription in atomic detail.

text: The carboxyl terminal domain (CTD) of RPB1, the largest subunit of RNA polymerase II, plays an important role in bringing together the machinery necessary for the synthesis and processing of Pol II transcripts.[11] Long and structurally disordered, the CTD contains multiple repeats of heptapeptide sequence YSPTSPS that are subject to phosphorylation and other posttranslational modifications during the transcription cycle. These modifications and their regulation constitute the operational code for the CTD to control transcription initiation, elongation and termination and to couple transcription and RNA processing.[11]

text: Initiation[edit]

text: The initiation of gene transcription in eukaryotes occurs in specific steps.[1] First, an RNA polymerase along with general transcription factors binds to the promoter region of the gene to form a closed complex called the preinitiation complex. The subsequent transition of the complex from the closed state to the open state results in the melting or separation of the two DNA strands and the positioning of the template strand to the active site of the RNA polymerase. Without the need of a primer, RNA polymerase can initiate the synthesis of a new RNA chain using the template DNA strand to guide ribonucleotide selection and polymerization chemistry.[1] However, many of the initiated syntheses are aborted before the transcripts reach a significant length (~10 nucleotides). During these abortive cycles, the polymerase keeps making and releasing short transcripts until it is able to produce a transcript that surpasses ten nucleotides in length. Once this threshold is attained, RNA polymerase passes the promoter and transcription proceeds to the elongation phase.[1]

text: Eukaryotic promoters and general transcription factors[edit]

text: Pol II-transcribed genes contain a region in the immediate vicinity of the transcription start site (TSS) that binds and positions the preinitiation complex. This region is called the core promoter because of its essential role in transcription initiation.[12][13] Different classes of sequence elements are found in the promoters. For example, the TATA box is the highly conserved DNA recognition sequence for the TATA box binding protein, TBP, whose binding initiates transcription complex assembly at many genes.

text: Eukaryotic genes also contain regulatory sequences beyond the core promoter. These cis-acting control elements bind transcriptional activators or repressors to increase or decrease transcription from the core promoter. Well-characterized regulatory elements include enhancers, silencers, and insulators. These regulatory sequences can be spread over a large genomic distance, sometimes located hundreds of kilobases from the core promoters.[1]

text: General transcription factors are a group of proteins involved in transcription initiation and regulation.[1] These factors typically have DNA-binding domains that bind specific sequence elements of the core promoter and help recruit RNA polymerase to the transcriptional start site. General transcription factors for RNA polymerase II include TFIID, TFIIA, TFIIB, TFIIF, TFIIE, and TFIIH.[1][14][15]

text: Assembly of preinitiation complex[edit]

text: To prepare for transcription, a complete set of general transcription factors and RNA polymerase need to be assembled at the core promoter to form the ~2 million dalton preinitiation complex.[16] For example, for promoters that contain a TATA box near the TSS, the recognition of TATA box by the TBP subunit of TFIID initiates the assembly of a transcription complex. The next proteins to enter are TFIIA and TFIIB, which stabilize the DNA-TFIID complex and recruit Pol II in association with TFIIF and additional transcription factors. TFIIF serves as the bridge between the TATA-bound TBP and polymerase. One of the last transcription factors to be recruited to the preinitiation complex is TFIIH, which plays an important role in promoter melting and escape.[17]

text: Promoter melting and open complex formation[edit]

text: For pol II-transcribed genes, and unlike bacterial RNA polymerase, promoter melting requires hydrolysis of ATP and is mediated by TFIIH.[17] TFIIH is a ten-subunit protein, including both ATPase and protein kinase activities.[18] While the upstream promoter DNA is held in a fixed position by TFIID, TFIIH pulls downstream double-stranded DNA into the cleft of the polymerase, driving the separation of DNA strands and the transition of the preinitiation complex from the closed to open state. TFIIB aids in open complex formation by binding the melted DNA and stabilizing the transcription bubble.

text: Abortive initiation[edit]

text: Once the initiation complex is open, the first ribonucleotide is brought into the active site to initiate the polymerization reaction in the absence of a primer.[1] This generates a nascent RNA chain that forms a hetero-duplex with the template DNA strand. However, before entering the elongation phase, polymerase may terminate prematurely and release a short, truncated transcript. This process is called abortive initiation.[19] Many cycles of abortive initiation may occur before the transcript grows to sufficient length to promote polymerase escape from the promoter. Throughout abortive initiation cycles, RNA polymerase remains bound to the promoter and pulls downstream DNA into its catalytic cleft in a scrunching-kind of motion.[19]

text: Promoter escape[edit]

text: When a transcript attains the threshold length of ten nucleotides, it enters the RNA exit channel.[1] The polymerase breaks its interactions with the promoter elements and any regulatory proteins associated with the initiation complex that it no longer needs.[20] Promoter escape in eukaryotes requires ATP hydrolysis and, in the case of Pol II-phosphorylation of the CTD. Meanwhile, the transcription bubble collapses down to 12-14 nucleotides, providing kinetic energy required for the escape.[1]

text: Elongation[edit]

text: After escaping the promoter and shedding most of the transcription factors for initiation, the polymerase acquires new factors for the next phase of transcription: elongation.[21][22] Transcription elongation is a processive process. Double stranded DNA that enters from the front of the enzyme is unzipped to avail the template strand for RNA synthesis. For every DNA base pair separated by the advancing polymerase, one hybrid RNA:DNA base pair is immediately formed. DNA strands and nascent RNA chain exit from separate channels; the two DNA strands reunite at the trailing end of the transcription bubble while the single strand RNA emerges alone.

text: Elongation factors[edit]

text: Among the proteins recruited to polymerase are elongation factors, thus called because they stimulate transcription elongation.[23] There are different classes of elongation factors. Some factors can increase the overall rate of transcribing, some can help the polymerase through transient pausing sites, and some can assist the polymerase to transcribe through chromatin.[24] One of the elongation factors, P-TEFb, is particularly important.[25] P-TEFb phosphorylates the second residue (Ser-2) of the CTD repeats (YSPTSPS) of the bound Pol II. P-TEFb also phosphorylates and activates SPT5 and TAT-SF1. SPT5 is a universal transcription factor that helps recruit 5'-capping enzyme to Pol II with a CTD phosphorylated at Ser-5. TAF-SF1 recruits components of the RNA splicing machinery to the Ser-2 phosphorylated CTD. P-TEFb also helps suppress transient pausing of polymerase when it encounters certain sequences immediately following initiation.[25]

text: Transcription fidelity[edit]

text: Transcription fidelity is achieved through multiple mechanisms. RNA polymerases select correct nucleoside triphosphate (NTP) substrate to prevent transcription errors. Only the NTP which correctly base pairs with the coding base in the DNA is admitted to the active center.[26][27] RNA polymerase performs two known proof reading functions to detect and remove misincorporated nucleotides: pyrophosphorylytic editing and hydrolytic editing.[1] The former removes the incorrectly inserted ribonucleotide by a simple reversal of the polymerization reaction, while the latter involves backtracking of the polymerase and cleaving of a segment of error-containing RNA product. Elongation factor TFIIS stimulates an inherent ribonuclease activity in the polymerase, allowing the removal of misincorporated bases through limited local RNA degradation.[28] Note that all reactions (phosphodiester bond synthesis, pyrophosphorolysis, phosphodiester bond hydrolysis) are performed by RNA polymerase by using a single active center.[29]

text: Pausing, poising, and backtracking[edit]

text: Transcription elongation is not a smooth ride along the DNA railway. For proofreading, the polymerase is made to back-up, erase some of the RNA it has already made and have another go at transcription.[1] In general, RNA polymerase does not transcribe through a gene at a constant pace. Rather it pauses periodically at certain sequences, sometimes for long periods of time before resuming transcription.[30] In extreme cases, for example, when the polymerase encounters a damaged nucleotide, it comes to a complete halt. More often, an elongating polymerase is stalled near the promoter.[30] Promoter-proximal pausing during early elongation is a commonly used mechanism for regulating genes poised to be expressed rapidly or in a coordinated fashion. Pausing is mediated by a complex called NELF (negative elongation factor) in collaboration with DSIF (DRB-sensitivity-inducing factor containing SPT4/SPT5).[31] The blockage is released once the polymerase receives an activation signal, such as the phosphorylation of Ser-2 of CTD tail by P-TEFb. Other elongation factors such as ELL and TFIIS stimulate the rate of elongation by limiting the length of time that polymerase pauses.[1]

text: RNA processing[edit]

text: Elongating polymerase is associated with a set of protein factors required for various types of RNA processing.[1] mRNA is capped as soon as it emerges from the RNA-exit channel of the polymerase. After capping, dephosphorylation of Ser-5 within the CTD repeats may be responsible for dissociation of the capping machinery. Further phosphorylation of Ser-2 causes recruitment of the RNA splicing machinery that catalyzes the removal of non-coding introns to generate mature mRNA.[1] Alternative splicing expands the protein complements in eukaryotes. Just as with 5’-capping and splicing, the CTD tail is involved in recruiting enzymes responsible for 3’-polyadenylation, the final RNA processing event that is coupled with the termination of transcription.[1]

text: Termination[edit]

text: The last stage of transcription is termination, which leads to the dissociation of the complete transcript and the release of RNA polymerase from the template DNA.The process differs for each of the three RNA polymerases.[32] The mechanism of termination is the least understood of the three transcription stages.

text: Factor-dependent[edit]

text: The termination of transcription of pre-rRNA genes by polymerase Pol I is performed by a system that needs a specific transcription termination factor.[3] The mechanism used bears some resemblance to the rho-dependent termination in prokaryotes.[33] Eukaryotic cells contain hundreds of ribosomal DNA repeats, sometimes distributed over multiple chromosomes. Termination of transcription occurs in the ribosomal intergenic spacer region that contains several transcription termination sites upstream of a Pol I pausing site. Through a yet unknown mechanism, the 3’-end of the transcript is cleaved, generating a large primary rRNA molecule that is further processed into the mature 18S, 5.8S and 28S rRNAs.

text: As Pol II reaches the end of a gene, two protein complexes carried by the CTD, CPSF (cleavage and polyadenylation specificity factor) and CSTF (cleavage stimulation factor), recognize the poly-A signal in the transcribed RNA.[32] Poly-A-bound CPSF and CSTF recruit other proteins to carry out RNA cleavage and then polyadenylation. Poly-A polymerase adds approximately 200 adenines to the cleaved 3’ end of the RNA without a template.[32] The long poly-A tail is unique to transcripts made by Pol II.

text: In the process of terminating transcription by Pol I and Pol II, the elongation complex does not dissolve immediately after the RNA is cleaved. The polymerase continues to move along the template, generating a second RNA molecule associated with the elongation complex.[1] Two models have been proposed to explain how termination is achieved at last.[32] The allosteric model states that when transcription proceeds through the termination sequence, it causes disassembly of elongation factors and/or an assembly of termination factors that cause conformational changes of the elongation complex.[33][34] The torpedo model suggests that a 5' to 3' exonuclease degrades the second RNA as it emerges from the elongation complex. Polymerase is released as the highly processive exonuclease overtakes it. It is proposed that an emerging view will express a merge of these two models.[34]

text: Factor-independent[edit]

text: RNA polymerase III can terminate transcription efficiently without the involvement of additional factors. The Pol III termination signal consists of a stretch of thymines (on the nontemplate strand) located within 40bp downstream from the 3' end of mature RNAs.[32] The poly-T termination signal pauses Pol III and causes it to backtrack to the nearest RNA hairpin to become a “dead-end” complex.[35] Consistent with the allosteric mechanism of termination,[36] the RNA hairpin allosterically opens Pol III and causes the elongation complex to disintegrate. The extensive structure embedded in the Pol III-transcript thus is responsible for the factor-independent release of Pol III at the end of a gene. RNA-duplex-dependent termination is an ancient mechanism that dates back to the last universal common ancestor.

text: Eukaryotic transcriptional control[edit]

text: The regulation of gene expression in eukaryotes is achieved through the interaction of several levels of control that acts both locally to turn on or off individual genes in response to a specific cellular need and globally to maintain a chromatin-wide gene expression pattern that shapes cell identity.[1][37] Because eukaryotic genome is wrapped around histones to form nucelosomes and higher-order chromatin structures, the substrates for transcriptional machinery are in general partially concealed.[1] Without regulatory proteins, many genes are expressed at low level or not expressed at all. Transcription requires displacement of the positioned nucleosomes to enable the transcriptional machinery to gain access of the DNA.[38]

text: All steps in the transcription are subject to some degree of regulation.[1] Transcription initiation in particular is the primary level at which gene expression is regulated. Targeting the rate-limiting initial step is the most efficient in terms of energy costs for the cell. Transcription initiation is regulated by cis-acting elements (enhancers, silencers, isolators) within the regulatory regions of the DNA, and sequence-specific trans-acting factors that act as activators or repressors.[1] Gene transcription can also be regulated post-initiation by targeting the movement of the elongating polymerase.[39]

text: Global control and epigenetic regulation[edit]

text: The eukaryotic genome is organized into a compact chromatin structure that allows only regulated access to DNA. The chromatin structure can be globally "open" and more transcriptionally permissive, or globally "condensed" and transcriptionally inactive. The former (euchromatin) is lightly packed and rich in genes under active transcription. The latter (heterochromatin) includes gene-poor regions such as telomeres and centromeres but also regions with normal gene density but transcriptionally silenced. Transcription can be silenced by histone modification (deaceltylation and methylation), RNA interference, and/or DNA methylation.[40]

text: The gene expression patterns that define cell identity are inherited through cell division.[1] This process is called epigenetic regulation. DNA methylation is reliably inherited through the action of maintenance methylases that modify the nascent DNA strand generated by replication.[1] In mammalian cells, DNA methylation is the primary marker of transcriptionally silenced regions. Specialized proteins can recognize the marker and recruit histone deacetylases and methylases to re-establish the silencing. Nucleosome histone modifications could also be inherited during cell division, however, it is not clear whether it can work independently without the direction by DNA methylation.[1]

text: Gene-specific activation[edit]

text: The two main tasks of transcription initiation are to provide RNA polymerase with an access to the promoter and to assemble general transcription factors with polymerase into a transcription initiation complex. Diverse mechanisms of initiating transcription by overriding inhibitory signals at the gene promoter have been identified.[1] Eukaryotic genes have acquired extensive regulatory sequences that encompass a large number of regulator-binding sites and spread overall kilobases (sometimes hundreds of kilobases) from the promoter–-both upstream and downstream.[1] The regulator binding sites are often clustered together into units called enhancers. Enhancers can facilitate highly cooperative action of several transcription factors (which constitute enhanceosomes). Remote enhancers allow transcription regulation at a distance. Insulators situated between enhancers and promoters help define the genes that an enhancer can or cannot influence.

text: Eukaryotic transcriptional activators have separate DNA-binding and activating functions.[1] Upon binding to its cis-element, an activator can recruit polymerase directly or recruit other factors needed by the transcriptional machinery. An activator can also recruit nucleosome modifiers that alter chromatin in the vicinity of the promoter and thereby help initiation. Multiple activators can work together, either by recruiting a common or two mutually dependent components of the transcriptional machinery, or by helping each other bind to their DNA sites.[1] These interactions can synergize multiple signaling inputs and produce intricate transcriptional responses to address cellular needs.

text: Gene-specific repression[edit]

text: Eukaryotic transcription repressors share some of the mechanisms used by their prokaryotic counterparts. For example, by binding to a site on DNA that overlaps with the binding site of an activator, a repressor can inhibit binding of the activator. But more frequently, eukaryotic repressors inhibit the function of an activator by masking its activating domain, preventing its nuclear localization, promoting its degradation, or inactivating it through chemical modifications.[1] Repressors can directly inhibit transcription initiation by binding to a site upstream of a promoter and interacting with the transcriptional machinery. Repressors can indirectly repress transcription by recruiting histone modifiers (deacetylases and methylases) or nucelosome remodeling enzymes that affect the accessibility of the DNA.[1] Repressing histone and DNA modifications are also the basis of transcriptional silencing that can spread along the chromatin and switch off multiple genes.[41]

text: Elongation and termination control[edit]

text: The elongation phase starts once assembly of the elongation complex has been completed, and progresses until a termination sequence is encountered.[1] The post-initiation movement of RNA polymerase is the target of another class of important regulatory mechanisms. For example, the transcriptional activator Tat affects elongation rather than initiation during its regulation of HIV transcription.[42] In fact, many eukaryotic genes are regulated by releasing a block to transcription elongation called promoter-proximal pausing.[43] Pausing can influence chromatin structure at promoters to facilitate gene activity and lead to rapid or synchronous transcriptional responses when cells are exposed to an activation signal.[30] Pausing is associated with the binding of two negative elongation factors, DSIF (SPT4/SPT5) and NELF, to the elongation complex. Other factors can also influence the stability and duration of the paused polymerase.[44] Pause release is triggered by the recruitment of the P-TEFb kinase.[39]

text: Transcription termination has also emerged as an important area of transcriptional regulation. Termination is coupled with the efficient recycling of polymerase.[45] The factors associated with transcription termination can also mediate gene looping and thereby determine the efficiency of re-initiation.

text: Transcription-coupled DNA repair[edit]

text: When transcription is arrested by the presence of a lesion in the transcribed strand of a gene, DNA repair proteins are recruited to the stalled RNA polymerase to initiate a process called transcription-coupled repair.[46] Central to this process is the general transcription factor TFIIH that has ATPase activity. TFIIH causes a conformational change in the polymerase, to expose the transcription bubble trapped inside, in order for the DNA repair enzymes to gain access to the lesion.[47] Thus, RNA polymerase serves as damage-sensing protein in the cell to target repair enzymes to genes that are being actively transcribed.

text: Comparisons between prokaryotic and eukaryotic transcription[edit]

text: Eukaryotic transcription is more complex than prokaryotic transcription. For instance, in eukaryotes the genetic material (DNA), and therefore transcription, is primarily localized to the nucleus, where it is separated from the cytoplasm (in which translation occurs) by the nuclear membrane. This allows for the temporal regulation of gene expression through the sequestration of the RNA in the nucleus, and allows for selective transport of mature RNAs to the cytoplasm. Bacteria do not have a distinct nucleus that separates DNA from ribosome and mRNA is translated into protein as soon as it is transcribed. The coupling between the two processes provides an important mechanism for prokaryotic gene regulation.[1]

text: At the level of initiation, RNA polymerase in prokaryotes (bacteria in particular) binds strongly to the promoter region and initiates a high basal rate of transcription. No ATP hydrolysis is needed for the close-to-open transition, promoter melting is driven by binding reactions that favor the melted conformation. Chromatin greatly impedes transcription in eukaryotes. Assembly of large multi-protein preinitiation complex is required for promoter-specific initiation. Promoter melting in eukaryotes requires hydrolysis of ATP. As a result, eukaryotic RNA polymerases exhibit a low basal rate of transcription initiation.[41]

text: Regulation of transcription in cancer[edit]

text: In vertebrates, the majority of gene promoters contain a CpG island with numerous CpG sites.[48] When many of a gene's promoter CpG sites are methylated the gene becomes silenced.[49] Colorectal cancers typically have 3 to 6 driver mutations and 33 to 66 hitchhiker or passenger mutations.[50] However, transcriptional silencing may be of more importance than mutation in causing progression to cancer. For example, in colorectal cancers about 600 to 800 genes are transcriptionally silenced by CpG island methylation (see regulation of transcription in cancer). Transcriptional repression in cancer can also occur by other epigenetic mechanisms, such as altered expression of microRNAs.[51] In breast cancer, transcriptional repression of BRCA1 may occur more frequently by over-expressed microRNA-182 than by hypermethylation of the BRCA1 promoter (see Low expression of BRCA1 in breast and ovarian cancers).