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Discuss the advantages of genetic variety within a species population?

How is gene activity regulated (e.g. lac operon)?

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Collen Von
Collen VonLv2
28 Sep 2019

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Related questions

Mention the components of bacterial transcriptional switches. The Lac operon is regulated by both activator CAP and Lac repressor. A scientist introduces a mutation in the gene encoding the activator CAP, making this allosteric protein insensitive to glucose levels. What outcomes do you expect if you culture the mutated bacteria in a culture medium with glucose and lactose. Give your explanation based on the mechanism of the Lac operon.

A theoretical operon (amo) in E. coli contains several structural genes encoding enzymes involved in the biosynthesis of a particular amino acid. Unlike the lac operon, in which the repressor gene is separate from the operon itself, for the amo operon, the repressor gene is found within the operon itself. When the end product amino acid is present, it binds to the repressor, and this complex binds to the operator, repressing the operon. In the absence of the amino acid, the repressor fails to bind to the operator, and transcription proceeds. Characterize this operon, comparing it to the regulation of the lac and trp operons. Be sure to discuss how regulation is affected by having the repressor gene as part of the operon.

Then, consider the following mutations:

a) Mutation in the operator region;

b) Mutation in the promoter region;

c) Mutation in the repressor gene.

In each case, state whether the operon will be transcribed or not, and describe how the mutation affects the regulation of the operon. Compare each response to the equivalent situation in the lac and trp operons.

Explain why (a) inactivation of the O2 or O3 sequence of the lac operon causes only a twofold loss in repression, and (b) inactivation of both O2 and O3 reduces repression 70-fold.

The following passage wasn't included with the question, but it might be helpful: "The lac operon actually contains three operator sequences to which lac repressor binds with high affinity, known as O1, O2, and O3. O1, the primary repressor-binding site, was identified through its protection by lac repressor from nuclease digestion. The 26-bp protected sequence lies within a nearly twofold symmetrical sequence of 35 bp. O1 overlaps the transcription start site of the lacZ gene. The operator sequence O2 is centered 401 bp downstream, fully within the lacZ gene, and O3 is centered 93 bp upstream.

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