Basics of Transcription Flashcards
When are the genes within the lac operon induced?
In the presence of low concentrations of glucose
Which subunit of prokaryotic RNA polymerase binds to UP elements within promoters?
Alpha
What is needed for BOTH intrinsic terminators and rho dependent terminators?
Hairpin formation
Which mutation behaves as a dominant negative in meridiploid bacteria?
I-d
Which process is needed for the lysogenic, but NOT lytic phase of lamda phage infection?
The integrase gene
Describe the behavior of the lambda repressor during lysogeny
It binds the operator to the right, the operator to the left, and PRM
In lambda phage, what is the function of N?
It is an antiterminator protein that binds to its own transcript
What are the three steps of transcription?
Initiation, Elongation, and Termination
What is the rate-limiting step of transcription?
Initiation
What are 3 requirements for RNA transcription?
- ) RNA polymerase enzyme
- ) Promoter sequence on the DNA template
- ) Ribonucleotides
What is the function of sigma?
Specificity factor; directs the polymerase to initiate transcription at specific promoters; promotes tight binding between RNA polymerase and promoters
What does the Nitrocellulose filter binding assay measure?
The dissociation rate of RNA polymerase-DNA complex
What is the importance of the +1 site?
It is where the first nucleotide is incorporated into RNA
What direction are nucleic acids synthesized in?
5’ to 3’
In what direction is the template strand read?
3’ to 5’
What are promoters?
DNA sequences where RNA polymerases bind to initiate transcription
What is the main function of the UP element?
Stabilizes interaction, increases transcription
What is the main function of the core promoter?
Recruits polymerase
What is the function of region 2.1?
Binds core
What is the function of region 2.4?
Promoter recognition at -10 box
Why are most promoters AT-rich?
It helps to initiate transcription, because AT-rich DNA is less stable than GC-rich DNA
What are the 2 domains that make up the alpha subunit?
alpha-NTD and alpha-CTD (connected by a linker)
What is the main function of the alpha-CTD domain?
Binds to UP element and provides tight binding between polymerase and promoter to produce high level of transcription
What is the function of terminators?
Located at the end of a gene; cause polymerase to fall off template, releasing template
What is the main difference between Intrinsic terminators and rho-dependent terminators?
Intrinsic terminators do not require any proteins, and rho-dependent terminators require rho
