11-11-09_translationA

11-11-09_translationA - We'd dub the one that came off best...

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We'd dub the one that came off best into the final transcription . It gave us a chance to ad lib as much as we wanted, knowing that excess ad libbing could be s(p)liced from the final product. Bing Crosby , rogue geneticist?
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Announcements Quiz 8 will come out today rather than yesterday
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Information flow in eukaryotes Replication and transcription take place in the nucleus Transcription is the copying of a DNA template to messenger RNA DNA mainly for information storage, RNA mainly for info. utilization Translation, or the creation of protein from a mRNA template, takes place in the cytoplasm/roughER
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RNA polymerases bind to promoter regions on DNA to start transcription Transcription factors such as CREB and c-fos recognize a DNA sequence, called the promoter region , upstream of the transcription start point and are activated by intracellular signals (e.g. PKA) Upstream means before the start point of transcription on the DNA, on the 3’ side of it. Downstream means after the start point, on the 5’ side. Promoter regions are often consensus sequences for DNA, meaning conserved DNA sequences with some slight variation in sequence and location upstream In bacteria, TTGACA is the -35 sequence, and TATAAT is the -10 sequence, or Pribnow box. The numbers refer to the number of base pairs upstream where the promoters are located.
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RNA polymerases add one RNA at at time from RNA-triphosphate precursors RNA polymerases move in a 3’ to 5’ direction along the DNA in order to be synthesized in a 5’ to 3’ direction They catalyze reaction: RNAn + NPPP —> RNAn+1 + PPi (—> 2 Pi)
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Bacterial transcription with E. coli bacteria as model organisms Sigma factor allows recognition of promoter site by polymerase “Crab claw” RNA polymerase (above left) “melts” DNA H-bonds between strands (helicase activity) The 15 base pair section of single strand DNA is called the transcription bubble.
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Sigma factor transiently associates with the promoter at the start of transcription in bacteria By itself, RNA polymerase randomly transcribes The polymerase and sigma factor together form a holoenzyme , which is a combination of a core enzyme and a recognition factor. Sigma factor binds reversibly at the promoter and allows transcription to initiate Sigma falls off DNA after RNA chain gets long enough Also a termination sequence called rho stops transcription. Other termination sequences also exist.
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TATA for now: TATA box is a common promoter sequence across mammalian species TATA box is shown in blue, transcription start at A in all 3 species Similar to the sigma factor in prokaryotes, there is a TATA binding protein in eukaryotes that allows other proteins to aggregate and start transcription.
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Ready, set, pre-initiate! Transcription factor for polymerase II,
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11-11-09_translationA - We'd dub the one that came off best...

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