Transcription & RNA Processing Flashcards
3 steps of transcription
initiation, elongation, termination
define promoter
sequence of double stranded DNA where RNA polymerase binds
when does initiation occur
when RNA polymerase binds to the promoter
what helps RNA polymerase bind to the promoter in eukaryotes?
transcription factors
transcription factors + RNA polymerase + promoter = ?
pre-initiation complex
How much of your genome is replicated right before your cells divide?
all of it
How much of your genome is converted to protein (transcribed, then translated)?
<2%
How much of your genome is converted to RNA (transcribed)?
80%
What are transcription factors?
proteins that bind to the promoter first and allow RNA polymerase to bind
What sort of sequence does a promoter usually contain? Why is this helpful?
T-A rich sequences called TATA boxes; easier to seaparate because they have fewer hydrogen bonds
What happens during elongation?
RNA polymerase starts moving along DNA strand and synthesizes the pre-mRNA transcript
Where do transcription factors go during elongation?
stay at the promoter
Why do transcription factors stay at the promoter? What does this allow?
allows another RNA polymerase to bind at the promoter and start transcribing another pre-mRNA transcript; this makes transcription faster and more efficient
How fast does RNA polymerase add nucleotides?
10-100 nucleotides / sec
What is the “sense” strand?
strand of DNA that is the same sequence as the pre-mRNA transcript
What is the “antisense” or “template” strand?
the strand of DNA that serves as the template for RNA polymerase
Which strand is “read” by RNA polymerase?
“antisense” strand
all “sense” strands are…
5’ —> 3’