Question

Which of the following choices is NOT a correct description of a reporter gene?

Question 29 options:

	None of the choices is correct.
	often fused to another protein to assess its activity
	a protein-encoding gene whose expression is easily quantifiable
	often fused to another gene's regulatory region to determine control

As a general principle of gene regulation through operons, regulatory genes encode _____________.

Question 28 options:

	trans-acting proteins that interact with trans-acting DNA elements
	cis-acting proteins that interact with cis-acting DNA elements
	trans-acting proteins that interact with cis-acting DNA elements
	cis-acting proteins that interact with trans-acting DNA elements

A common amino acid motif found in many of the polypeptides that function as repressors is ______________.

Question 27 options:

	Leucine zipper motif
	Helix-turn-helix motif
	Zinc finger motif
	Helix-loop-helix motif

How do negative regulators such as the lac repressor prevent RNA polymerase from initiating transcription?

Question 26 options:

	by forming a loop in the operator that restricts the passage of the polymerase
	by binding to the polymerase, thus preventing its binding
	by blocking passage of the polymerase through the operator
	by physically blocking the DNA binding site of RNA polymerase

The critical step in the regulation of most bacterial genes occurs _____________.

Question 25 options:

	at release of mRNA
	during transcription
	during translation
	post-translationally

Answer 1

29. None of the choice is correct.

Reporter genes are nucleic acid sequences that code for easily assayed proteins. They can be fused to another gene's regulatory regions for the assessment of its activity. Some of the commonly used reporter genes are: GFP (Green Fluorescent Protein), RFP (Red Fluorescent Protein).

28. Trans-acting proteins that interact with cis-acting DNA elements.

In operons, regulatory genes are present upstream of structural gene, which expression is to be regulated by regulatory genes. It codes for repressor genes which regulate the transcription of operon products.

27. Helix-turn-helix motif

Repressor protein binds to operator and restricts gene expression. Helix turn helix is a DNA binding motif, so it is found in most of the repressor proteins.

26. By forming a loop in the operator that restricts the passage of the polymerase.

Repressor protein binds with the operator region, present between promoter region and structural gene. It blocks the attachment of RNA polymerase with the promoter region, thus repressing the transcription.

25. during transcription

Gene regulation in prokaryotes is done at transcription level mainly, by the presence of operons like lac operon. No specific modifications are done at the release of mRNA or during translation as in the case of eukaryotes.