Question 1 (1 point) Which of the following situations would stimulate transcrip

Question

Question 1 (1 point)

Which of the following situations would stimulate transcription of the lactose operon in E. coli?

Question 1 options:

A mutation in the repressor gene that weakens the affinity of the repressor for the inducer.

A mutation in the repressor gene that weakens the affinity of the repressor for the operator.

A mutation in the repressor gene that strengthens the affinity of the repressor for the operator.

The presence of glucose in the growth medium.

Binding of the repressor to the operator.

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Question 2 (1 point)

Which is not a characteristic of the cAMP receptor protein (CRP)?

Question 2 options:

It is a positive regulator of the lac operon.

In the situation in which the cell has sufficient glucose and lactose, CRP will not be bound to the CRP binding site near the promoter of the operon.

CRP binding near the promoter site is dependent on the prior binding of cAMP to CRP.

The binding of CRP to DNA only occurs at the lac operon.

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A mutation in the repressor gene that weakens the affinity of the repressor for the inducer.

A mutation in the repressor gene that weakens the affinity of the repressor for the operator.

A mutation in the repressor gene that strengthens the affinity of the repressor for the operator.

The presence of glucose in the growth medium.

Binding of the repressor to the operator.

Explanation / Answer

1) The correct option is A mutation in the repressor gene that weakens the affinity of the repressor for the operator.

Transcription of the lactose operon in E. coli is stimulated by the process of mutation in the repressor gene, which weakens the affinity of the repressor for the operator.

2) The correct option is The binding of CRP to DNA only occurs at the lac operon.

In the lactose operon of the final targets of glucose are the lac repressor, which is the positive regulator, the complex of cAMP receptor protein and cAMP. When both glucose and lactose were present, then the bacteria use the available glucose and the lac operon remains turned off . CRP does not bind to the promoter region when glucose is present. As there is no enough CRP to bind to CAP and cannot bind to the activator binding site, therefore, RNA polymerase cannot transcribe.

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