Transcription in Prokaryotes Flashcards
RNA polymerase reads and synthesizes in..
reads template in 3’ to 5’ direction and synthesizes from 5’ to 3’
RNA polymerases uses…
ribonycleoside triphosphate (atp, gtp) and releases put-phosphate
RNA polymerase does not require a _____ and has no _____
primer and no nuclease activity (no proofreading)
RNAP subunits
- core enzyme
2. Sigma factor
RNAP subunits- Core enzyme structure
formed of 5 subunits
2 identical alpha subunits
2 similar beta subunits
1 omega subunit
RNAP subunits- core enzyme activity
responsible for 5’ -> 3’ RNA polymerase activity and can’t recognize promotor
RNAP subunits- sigma factor
enables RNAP to recognize and bind to promotor by increases the affinity of the enzyme to the promotor
holoenzyme complex
core enzyme + sigma factor
sequence of prokaryotic promotor
consensus sequence
consensus sequence
stable; specific sequence of nucleotides that play same role in different locations in genome
how are consensus sequences recognized
RNAP-alpha complex
consensus sequence include:
- -35 sequence
2. TATA (pribnow) box
consensus sequence; -35 Sequence and location
located 35 nucleotides upstream from start point
contains the sequence 5’ TTGACA 3’
consensus sequence; TATA (pribnow) box sequence and location
located 10 nucleotides upstream start point
contains sequence 5’ TATAAT 3’
mutation of consensus sequences : -35 sequence and TATA box effects
can affect transcription of gene because gene is controlled by mutant promoter
