What effect would a loss of function mutation in the lacI gene and a mutation in operator that prevents repressor binding have?

Table 1

Naturally occurring
L	TreR
P	GalR	GalS
Y	FruR	ExuR
T	AraR

What is the effect of mutation on gene expression?

Sometimes, gene variants (also known as mutations) prevent one or more proteins from working properly. By changing a gene’s instructions for making a protein, a variant can cause a protein to malfunction or to not be produced at all.

What would happen if there was a mutation in the regulatory gene for the lac operon so that the regulatory protein did not bind to lactose sugar?

An “up” mutation would make the lac operon no longer dependent on the positive regulation by the cAMP‑CAP complex (when the operon is induced). A “down” mutation would not allow expression even in the de‑repressed state (presence of inducer) and hence would show a non‑inducible phenotype.

What would be the effect of a mutation in the operator sequence of the lac operon so that the lac repressor protein could not bind?

ANS: A mutation that prevented the lac repressor from binding to the operator would make the lac operon constitutive only in the absence of glucose. However, this mutation would not be entirely constitutive because transcription would be inhibited in the presence of glucose.

What effect would you expect if gene expression of the lac operon were completely repressed?

What effect would you expect if gene expression of the lac operon was completely repressed? The cell would be more efficient without wasting’ the energy required for the low level of Lac Z, Lac Y, and Lac A gene expression. Allolactose would accumulate within the cell and become toxic.

How does glucose affect the lac operon?

How does glucose effect the lac operon? A) When glucose levels are high, glucose binds to and deactivates the repressor, preventing it from binding to the DNA.

How can gene mutations disrupt cellular processes?

A gene mutation can affect the cell in many ways. Some mutations stop a protein from being made at all. Others may change the protein that is made so that it no longer works the way it should or it may not even work at all. Some mutations may cause a gene to be turned on, and make more of the protein than usual.

What is the effect on transcription of the structural and regulatory genes of the lac operon When lactose is present in the environment?

Transcription of the structural genes occurs, Lactose changes the structure of the repressor such that it is unable to bind to the operator site, which in turn allows RNA polymerase to transcribe the structural genes.

What would happen if the operator sequence of the lac operon contains a mutation?

What would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator? In the presence of lactose, the lac operon will not be transcribed. In the absence of lactose, the lac operon will be transcribed.

How does cAMP affect the expression of the lac operon?

How does cAMP affect the expression of the lac operon? cAMP binds to the CRP, decreasing its affinity for a DNA site near the promoter. cAMP binds to the Lac repressor, decreasing its affinity for a DNA site near the promoter. cAMP binds to the Lac repressor, increasing its affinity for a DNA site near the promoter.

What happens if lac operon is removed?

What happens if the promoter region is removed from the lac operon? The structural genes would only be expressed in the absence of the repressor. The ligand binds to the regulator protein. And In the absence of the ligand, the regulator does not bind to the operator.