Transcription- Lecture Flashcards
Transcription is what to what
DNA to RNA (specifically mRNA)
What do stem cells do?
Regenerate any cell in the body and express telomerase
Replicating ends of DNA molecules
- in most cells the terminal nonreplicated nucleotides are removed and the chromosome is shortened
- in stem cells the enzyme telomerase uses an RNA template to extend the telomere
- telomerase moves to the new end and DNA polymerase fills the gap
What are the 3 basic steps of transcription?
1) initiation
2) elongation
3) termination
What is the enzyme in charge of transcription?
RNA polymerase
What are the characteristics of RNA polymerase?
Can only grow on 3’ end
In prokaryotes- can do by itself unlike DNA and doesn’t need primer
What are promoter elements and what is their job?
Special sequence of DNA
Signal RNA polymerase to bind and start transcription
Flags down RNA polymerase
Where does transcription start?
Start point
What happens at the start point?
Transcription factors bind (bind promoter specifically to consensus sequence) and then RNA polymerase bunds
What is the function of transcription?
Bind DNA and signal RNA polymerase
What are the 3 steps of initiation?
1) Eukaryotic promoter
2) transcription factors bind to DNA
3) transcription initiation complex forms
Elongation steps
- nontemplate strand of DNA, RNA nucleotides added (U not T)
- RNA polymerase unwinds 10-20 strands and adds newly made RNA
- polymerases line up on a DNA strand (train)
- —simultaneously bind DNA for multiple copies of same RNA
Why do we need multiple copies of RNA?
Needs lots of message to be more efficient and there is a less chance of it being degraded
Termination in prokaryotes
Terminator sequence, RNA polymerase detaches
Termination in eukaryotes
Polyadenylation signal (AAUAAAAA), 35 nucleotides detach
Termination- completed RNA transcript- direction of transcription ("downstream")
