transcription Flashcards
what is transcription?
The making of an RNA copy (transcript) of one strand of DNA
how is RNA copied?
The RNA transcript is copied from a template strand of DNA by RNA polymerase
how are strands of RNA read?
5’-3’
waht helps trancribe DNA to RNA?
RNA polymerase
what type of enzyme is RNA polymerase?
DNA-directed RNA polymerase
what does RNA polymerase do?
Separates the DNA strands (approx. 14 base pair transcription bubble)
Allows ribonucleoside triphosphates to base-pair with the template strand and catalyzes phosphodiester bond formation
8 nucleotides remain paired in the transcription bubble
what are the 4 steps of transcription?
promoter discovery, formation of the initial RNA, RNA chain elongation, RNA chain determination
what needs to be found before transcription can begin?
promoter sequence
how does bacterial polymerase get to the promoter?
goes directly to the promoter. The holoenzyme interacts with DNA and through hopping it searches to find its promoter
how does eukaryotic polymerase find the promoter?
needs help to get to the promoter. Rely on general transcription factors to find the promoter region.
what is the closed complex?
the initial complex formed between RNA polymerase and DNA. the DNA strands have not been separated (no bubble has been formed)
what is the open complex?
DNA strands are separated from each other. Rate limiting step
which complex is RNA synthesis carried out by?
open complex
once the open complex is formed, how many ribonucleoside triphosphates are joined while polymerase is still at the promoter?
8
in eukaryotes what is the process by which the promoter changes to leave?
phosphorylation
