CBIO 3400 Lecture Notes - Lecture 6: Rna Polymerase Ii, Tata Box, Tata-Binding Protein
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Exam 4 Lecture 6
Transcription: The 3 Main Steps of Eukaryotic Transcription
1. Initiation- transcription factors adhere to the TATA box in the promoter signaling RNA
polymerase II to attach. Additional transcription factors attach and the transcription
initiation complex is formed. Enhancers/silencers
a. Transcription factors are recruited to promoters; help perform the initial
decision if we should make an RNA from this coding region or not.
b. Most critical first step
2. Elongation- RNA Polymerase II unzips the DNA and pairs the template with
complementary mRNA nucleotides.
3. Termination- RNA Polymerase II reaches the polyadenylation (AAUAA) sequence and
releases the pre-mRNA.
a. Decision to stop transcription
b. Different from prokaryotes to eukaryotes*
Transcription: Major Questions to Answer
• How do we know where to start? Promoters
o Promoters are upstream
▪ UTRs (untranslated regions)
o Intensity of transcription can be dictated by promoters
• What factors are needed to bring the RNA Polymerase to the gene? Transcription
o Transcription factors- they can read the DNA to determine if they should bind to
and activate transcription from a particular gene.
o Each element below has a consensus sequence associated with it. General
association of nucleotides.
▪ Consensus sequence- dominant nucleotides
o BRE: B recognition element
o TATA: Its made of T’s and A’s
▪ Recognizes and binds to TATA box; TBP + 10 TBP associated factors;
▪ When TBP binds to DNA, it induces a curvature.
▪ T and A’s are less stable than Gs and Cs
o INR: Initiator element
o DPE: Downstream promoter element
o TFIIA binds and stabilizes the TFIID complex.
o TFIIB binds to BRE. Major component that recruits the RNA to the locus we are
going to transcribe. Also determines the start site of transcription. **
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