Question

A transcriptional control mechanism would

A.

modify a protein thereby changing the activity of the protein.

B.

manipulate the ability of RNA polymerase to carry out its function.

C.

influence ribosome function.

D.

result in degradation of a transcript.

Answer 1

A transcriptional control ( regulation) mechanism regulate the transcription i.e formation of RNA from DNA. As the transcription is done by RNA polymerase transcriptional control will regulate the RNA polymerase to control transcription. So these control by manipulating ( either increasing or hindering) the ability of RNA polymerase to carry out its function. There are three different kind of regulatory molecules activators and repressor and inducer in prokaryotes. Activators bind to the the promoter site and increase the rate of transcription. Repressor on the other hand bind to the the operator gene and prevent the transcription. Example of transcriptional regulation is seen in lac operon in prokaryotes. In lac operon regulatory gene make repressor protein that will bind to to operator gene and does not allow the transcription of structural genes to proceed by RNA polymerase as I could not move to structural gene . On the other hand when inducer is present it will bind to repressor protein so does not allow this repressor protein to bind to to operator gene. So operator gene remain functional and RNA polymerase can move to structural genes and transcription of structural genes proceeds.

So as all these regulatory molecules repressor, inducer and activator change activity of RNA polymerase to regulate translation. So option B) is right choice of this question.