Basics of Transcription

Question 1

When are the genes within the lac operon induced?

Answer 1

In the presence of low concentrations of glucose

Question 2

Which subunit of prokaryotic RNA polymerase binds to UP elements within promoters?

Answer 2

Alpha

Question 3

What is needed for BOTH intrinsic terminators and rho dependent terminators?

Answer 3

Hairpin formation

Question 4

Which mutation behaves as a dominant negative in meridiploid bacteria?

Answer 4

I-d

Question 5

Which process is needed for the lysogenic, but NOT lytic phase of lamda phage infection?

Answer 5

The integrase gene

Question 6

Describe the behavior of the lambda repressor during lysogeny

Answer 6

It binds the operator to the right, the operator to the left, and PRM

Question 7

In lambda phage, what is the function of N?

Answer 7

It is an antiterminator protein that binds to its own transcript

Question 8

What are the three steps of transcription?

Answer 8

Initiation, Elongation, and Termination

Question 9

What is the rate-limiting step of transcription?

Answer 9

Initiation

Question 10

What are 3 requirements for RNA transcription?

Answer 10

1. ) RNA polymerase enzyme
2. ) Promoter sequence on the DNA template
3. ) Ribonucleotides

Question 11

What is the function of sigma?

Answer 11

Specificity factor; directs the polymerase to initiate transcription at specific promoters; promotes tight binding between RNA polymerase and promoters

Question 12

What does the Nitrocellulose filter binding assay measure?

Answer 12

The dissociation rate of RNA polymerase-DNA complex

Question 13

What is the importance of the +1 site?

Answer 13

It is where the first nucleotide is incorporated into RNA

Question 14

What direction are nucleic acids synthesized in?

Answer 14

5’ to 3’

Question 15

In what direction is the template strand read?

Answer 15

3’ to 5’

Question 16

What are promoters?

Answer 16

DNA sequences where RNA polymerases bind to initiate transcription

Question 17

What is the main function of the UP element?

Answer 17

Stabilizes interaction, increases transcription

Question 18

What is the main function of the core promoter?

Answer 18

Recruits polymerase

Question 19

What is the function of region 2.1?

Answer 19

Binds core

Question 20

What is the function of region 2.4?

Answer 20

Promoter recognition at -10 box

Question 21

Why are most promoters AT-rich?

Answer 21

It helps to initiate transcription, because AT-rich DNA is less stable than GC-rich DNA

Question 22

What are the 2 domains that make up the alpha subunit?

Answer 22

alpha-NTD and alpha-CTD (connected by a linker)

Question 23

What is the main function of the alpha-CTD domain?

Answer 23

Binds to UP element and provides tight binding between polymerase and promoter to produce high level of transcription

Question 24

What is the function of terminators?

Answer 24

Located at the end of a gene; cause polymerase to fall off template, releasing template

Question 25

What is the main difference between Intrinsic terminators and rho-dependent terminators?

Answer 25

Intrinsic terminators do not require any proteins, and rho-dependent terminators require rho