Lecture 7 - Transcription in Eukaryotes, Regulation, and Epigenetics Flashcards
what are the differences of eukaryotic transcription compared to prokaryotes?
bacteria have 1 RNA Pol while eukary have 3; bacterial RNA Pol can initiate without anything while eukary needs transcription factors; eukary DNA is packed into histones and chromatin; regulatory proteins can act on a gene many nucleotides away
what genes does RNA Pol 1 transcribe?
most rRNA genes
what genes does RNA Pol 2 transcribe?
protein coding genes
what genes does RNA Pol 3 transcribe?
tRNA, 5S rRNA, structural genes for RNA
what else does RNA Pol require for mRNA transcription?
transcription factors unlike transcription in prokaryotes
what is TBP?
used in initiation; TBP is TATA binding protein which recognizes the TATA box
what is TF2A?
initiation; stabilizes binding of TBP and TF2B to promoter
what is TF2B?
initiation; binds to TBP, then recruits TF2F-Pol 2 complex
what is TF2E?
initiation; recruits TF2H; has ATPase and helicase properties
what is TF2F?
initiation; binds to Pol 2 and binds to TF2B, it prevents binding of Pol 2 to other sequences
what is TF2H?
initiation; has protein kinase activity = phosphorylates Pol 2 at CTD by adding phosphate groups that allow Pol 2 to separate from transcription factors, helicase activity = unwinding;recruits nucleotide excision repair proteins
what happens during the assembly of RNA polymerase at promoter? which enzymes involved?
TBP along with other proteins bind to the TATA box to form a multiprotein complex, then TF2H acts as helicase and unwinds the DNA at the promoter
what is CTD?
CTD is the carboxyl terminal domain which is were RNA Pol2 starts transcribing after it is phosphorylated by TF2H
What happens to RNA Pol 2 during elongation?
elongation factors bind to RNA Pol2 which helps it proceed with transcription
what happens at termination of RNA Pol2?
Termination occurs by binding of termination factors that remove elongation factors from RNA Pol 2; also it gets dephosphorylated
Do transcribed genes or silent genes get repaired more often?
transcribed genes repaired more often because they are useful
How is TF2H part of the repair process?
TF2H can recruit the NER or nucleotide excision repair complex at a lesion. genetic repair defects are associated with TF2H defects
How is DNA packed?
DNA is packed into nucleosomes and chromatin using histones which are positively charged.