Questions from Prokaryotic Transcription 1. The two main bacterial promoter cis
ID: 279689 • Letter: Q
Question
Questions from Prokaryotic Transcription 1. The two main bacterial promoter cis elements (TATAAT and TTGACA) are located where with respect to the transcription start site? -35 - lo negative CA 16-1968 TATAAT 5-9bp negative direction 2. What does a sigma factor do for a bacterial RNA polymerase? 3. If a repressor protein binds to the promoter region of the lac operon, transcription of that mRNA cannot occur. How does the repressor prevent transcription? 4. If you incubated an E. coli culture for several hours in a medium containing lactose and glucose as the only carbon sources (sources of nitrogen, phosphates, and trace elements would be included), the bacteria would grow fine. If you tested the solution after a few hours of incubation, which of the two carbon sources would be in high or low concentrations? 5. When does the CAP protein bind to its recognition site near the promoter of a bacterial gene?Explanation / Answer
Answer =
1.The two main bacterial promoter cis elements = (TATAAT) is located at the -10 (10 bp 5' or upstream ) from the transcription start site.
TTGACA is located -35 position from the transcription start site.
2.Role of sigma factor in bacterial transcription = Sigma factors are bacterial transcription factors that bind core RNA polymerase and direct transcription initiation at cognate promoter sites.
3.Repressor is a protein that represses of inhibits the transcription of the lac operon.If a repressor protein binds to the promoter region of the lac operon,transcription of that mRNA can not occur .
the repressor prevents the transcription by ,binding to promoter region .and promoter region is the site where RNA polymerase binds.repressor does not allow the RNA polymerase to bind.RNA polymerase does not bind hence transcription of mRNA can not occur .
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.