Question

1.) Which of the following are elements involved in eukaryotic transcriptional regulation?

a.) All of the choices are correct

b.) promoters

c.)enhancers

d.)silencers

e.)transcriptional elements

2.) The tryptophan operon is repressible opeon that is

a.) turned off whenever tryptophan is added to the growth medium.

b.)turned on only when tryptophan is present in the growth medium.

c.) permanently turned on.

d.) turned on only when glucose is present in the growth medium

Answer 1

1.The correct answer is a) all of the choices are correct. Eukaryotic transcription regulation involves many types of regulatory factors.

1. Promoter sequence provide the initiation of the transcription.
2. Enhancer are the DNA sequence that promotes the transcription. Enhancer change the shape of the DNA and help in interactions between the activators and transcription factors.
3. The silence perform exactly the opposite function of the enhancers. These are the DNA sequences that bind the repressors.
4. Transcription factors are DNA binding proteins that It helped to regulate the expression of a given gene. Thus is all factors are necessary for transcription regulation.

2.The correct answer is a) p turned off whenever tryptophan is added to the growth medium. When the tryptophan is added to the medium two molecules of tryptophan binds with the trp repressor. This results in the change in the shape of the repressor which makes it capable of binding to the operator site. This prevents the RNA polymer from binding and prevents the transcription.

1. Tryptophan operon is not turned on by the presence of tryptophan.
2. Tryptophan operon is turned on or turned off only due to presence or absence of tryptophan it is never permanently turned on.
3. Tryptophan operon is not regulated by presence of glucose. These options are incorrect.

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