Question

1. Which of the following conditions does not lead to a change in gene expression patterns in bacteria cells?

A.

Sporulation

B.

Heat shock

C.

Nutrient availability

D.

Nitrogen deprivation

E.

None of the choices are correct

2. Predict the outcome of the removal of the N form the DNA sequence of the (lamda) phage:

A.

Lysogenic cycle will be induced

B.

Entry into the bacterial host will be blocked

C.

Antitermination will be affected

D.

Transcription form the left promoter will be interrupted

E.

Antitermination will be affected and transcription form the left promoter will be interrupted

3. Which of the following is a possible mechanism for the action of NusA in termination?

A.

It binds to the RNA polymerase causing it to stall.

B.

It stimulates termination at intrinsic terminator by facilitating hairpin loop formation

C.

It binds to NusB to promote detachment of the RNA polymerase for the DNA template

D.

It interacts with S10 to promote dissociation of the RNA polymerase

E.

It binds to the RNA polymerase causing it to stall and it stimulates termination at intrinsic terminator by facilitating hairpin loop formation

Answer 1

1) A

A) Sporulation :- Spores are multilayered structure that tend to dormant the bacteria. these charecterestics of spores preserve the genetic content of the organism during harse environmentslconditions like extreme heat, nitrogen deprevation which leads to nutrient dipletion.

2)E

E) In DNA sequence N protein is a antiterminator. If N protein removed from DNA sequence antiterminator would be affected and trancscription form the left promotor will be interrupted because N protein is one of the gene in left promototer reading frame.

3) E.

NusA play a role in supressing termination in ribosomal RNA operons, which contain RNA sites resembling lambda NUT. i.e the lamda Q anti-terminater protein bind to DNA sequences just upstrean to the lambda right promoter and contact the RNAP stalled. And NusA stimulates hairpin formation by weakening the contacts between the ascending loop of the hairpin and to lesser extent by prolonging pausing at the termination point