Question

Some mutations can disable genes. What might be the result of such a mutation within the lac I regulatory region of the lac operon? If a lac I mutation was to occur, then an absence of repressor might occur. This would me that the cell is making proteins and wasting energy for no purpose.

Answer 1

This would mean that the cell is making proteins and wasting energy for no purpose.

Step-by-step explanation:

A mutation can be defined as a sort of changes that sometimes occurs in a situation where DNA is been copied due to some environmental factors which inturn affect the DNA sequence.

MUTATIONS can also happen in a situation in which a DNA gene is damaged to the extent that it alter the genetic message carried by that gene.

Therefore if some MUTATION can disable genes what might be the result of such a mutation within the lac I regulatory region of the lac operon would mean that the cell is making proteins and wasting energy for no purpose due to the fact the protein the cell is making is way higher which inturn cause the energy to be wasted without cause, reason or purpose.

Answer 2

Glucose present, lactose absent: transcription of the lac operon does not occur. That is because the lac repressor remains attached to the operator and prevents transcription by RNA polymerase. In addition, cAMP levels are low because glucose levels are high, so CAP is inactive and cannot bind to DNA.

_ Modified image of "Prokaryotic gene regulation: Figure 3", by OpenStax College, Biology (CC BY 4.0) ._

Glucose present, lactose present: transcription of the lac operon is given at a low level. The lac repressor is released from the operator because the inducer (alolactose) is present. CAMP levels, however, are low because there is glucose. Then, CAP remains inactive and cannot bind to DNA, so transcription only occurs at a low or poor level.

Glucose present, lactose present: low level transcription of operon * lac * occurs. The * lac * repressor is released from the operator because the inducer (alolactose) is present. CAMP levels, however, are low because glucose is present. So, CAP remains inactive and cannot bind to DNA, so transcription only occurs at a low or poor level.

Glucose present, lactose present: low level transcription of the lac operon occurs. The lac repressor is released from the operator because the inducer (alolactose) is present. CAMP levels, however, are low because glucose is present. So, CAP remains inactive and cannot bind to DNA, so transcription only occurs at a low or poor level.

_ Modified image of "Prokaryotic gene regulation: Figure 3", by OpenStax College, Biology (CC BY 4.0) ._

Glucose absent, lactose absent: transcription of the lac operon does not occur. CAMP levels are high because glucose levels are low, so CAP is active and will be bound to DNA. However, the lac repressor will also be attached to the operator (due to the absence of alolactose), and acts as a barrier to RNA polymerase and prevents transcription.

Glucose absent, lactose absent: transcription of operon * lac * does not occur. CAMP levels are high because glucose levels are low, so CAP is active and will be bound to DNA. However, the * lac * repressor will also be linked to the operator (due to the absence of alolactose), so it acts as a barrier to RNA polymerase and prevents transcription.

Glucose absent, lactose absent: transcription of the lac operon does not occur. CAMP levels are high because glucose levels are low, so CAP is active and will be bound to DNA. However, the lac repressor will also be linked to the operator (due to the absence of alolactose), so it acts as a barrier to RNA polymerase and prevents transcription.

_ Modified image of "Prokaryotic gene regulation: Figure 3", by OpenStax College, Biology (CC BY 4.0) ._

Glucose absent, lactose present: a strong transcription of the lac operon occurs. The lac repressor is released from the operator because the inducer (alolactose) is present. CAMP levels are high because there is no glucose, so CAP is active and bound to DNA. CAP helps RNA polymerase bind to the promoter, allowing high levels of transcription