To accomplish regulation in prokaryotes, operons (segments of DNA) include speci

Question

To accomplish regulation in prokaryotes, operons (segments of DNA) include specialized regions where a variety of regulatory proteins bind and detach to either initiate or inhibit transcription of the genes on that segment. (a) Identify two of the proteins involved in the gene regulation in prokaryotes and their function. (b) Describe the properties of the repressor that demonstrate it to be a protein. (c) Discuss the evidence that proves it to be a repressor within the operon. (d) Compare and contrast the roles of a repressor in an inducible system vs. its role in a repressible system.

Explanation / Answer

Answer:

a. Two proteins involved in the gene regulation in prokaryotes:

i. Repressor protein:

The repressor binds to the operator and blocks attachment of RNA polymerase to the promoter, preventing transcription of the genes. A repressor protein is specific for the operator of a particular operon.

ii. CAP:

CAP refers to catabolite activator protein, and is a regulatory protein that binds to DNA and stimulates transcription of a gene.

b. Properties of the repressor that demonstrate it to be a protein are:

i. Mutations could be isolated which can function in trans

ii. The gene products are proteins

iii. The repressor protein only binds to DNA with lac O+ region

c. The repressor binds to the operator and blocks attachment of RNA polymerase to the promoter, preventing transcription of the genes. A repressor protein is specific for the operator of a particular operon.

d. Both types of operons use a repressor protein that binds to the operator to turn the genes off. Both types of operons are affected by a specific molecule (either inducer or corepressor). This occurs by changing the shape of the repressor protein.

In an inducible operon, the genes are turned on in the presence of specific molecule (inducer). In a repressible operon, the genes are turned on in the absence of specific molecule (corepressor).

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.