What would be the result of a mutation in the repressor...

Name: Problem 45, Chapter 16: Biology for AP Courses
Uploaded: 2019-08-29T14:05:58-08:00
Duration: 4 min 26 s
Channel: Nalvi Duro
Description: What would be the result of a mutation in the repressor protein that prevented it from binding lactose? a. The repressor will bind to lactose when it is removed from the operator. b. The repressor will bind the operator in the presence of lactose. c. The repressor will not bind the operator in the presence of lactose. d. The repressor will not bind the operator in the absence of lactose.

What would be the result of a mutation in the repressor protein that prevented it from binding lactose? a. The repressor will bind to lactose when it is removed from the operator. b. The repressor will bind the operator in the presence of lactose. c. The repressor will not bind the operator in the presence of lactose. d. The repressor will not bind the operator in the absence of lactose.

What would be the result of a mutation in the repressor protein that prevented it from binding lactose?
a. The repressor will bind to lactose when it is removed from the operator.
b. The repressor will bind the operator in the presence of lactose.
c. The repressor will not bind the operator in the presence of lactose.
d. The repressor will not bind the operator in the absence of lactose.

Key Concepts

Lac Operon

The lac operon is a classic model of gene regulation in prokaryotes, where a cluster of genes is regulated collectively. Its expression is controlled by interactions between regulatory proteins and DNA sequences, enabling the organism to efficiently utilize available nutrients.

Repressor Protein

Repressor proteins are regulatory proteins that bind to specific DNA sequences known as operators to prevent transcription. Their binding activity is often modulated by the presence of specific molecules, ensuring that gene expression is repressed or activated in accordance with cellular needs.

Allosteric Regulation

Allosteric regulation involves the modulation of a protein's activity through the binding of an effector molecule at a site other than the protein's active site. This binding leads to structural changes that can alter the protein's function, such as preventing a repressor from binding to DNA.

Mutation Effects on Protein Function

Mutations in proteins can alter their structure and function, potentially disrupting critical interactions such as the binding of an inducer molecule. When a mutation prevents a regulatory protein from binding its effector, it can lead to continuous or unregulated gene activity, impacting cellular processes.

Transcript

00:01 We are being asked to determine what would happen to the repressor in the lack operon if the binding of the repressor to lactose is deficient.

00:11 So let's put that in context a little bit.

00:14 Up here, up top, we have the lack operon, which is basically the genes.

00:21 So the genes lack z, lack y, and lack a, those are genes that make enzymes that can consume lactose, that can break down lactose.

00:30 And the operon also has a cap binding site which acts as a promoter and which binds to the cap protein which adds as a promoter.

00:40 And it has an operator site to which the repressor bind, which represses the production of the enzymes that consume lactose.

00:50 And the reason that the cell wants to control this is because if there's glucose, it would preferentially consume glucose because glucose is a simpler sugar.

01:00 It provides more efficient energy than lactose.

01:04 So when there's glucose present, you don't want to be making lactose.

01:08 When there is no glucose and there is lactose, then you want to go ahead and consume lactose.

01:14 So the cell needs two factors to be, it needs to be able to differentiate these two factors in order to turn the operon on.

01:24 So the first case here in low glucose and high lactose, you have the cap protein on and you have the repressor.

01:34 So the repressor is drawn on the bottom here as this brownish rectangle, but it's not up top here where the rna polymerase is binding because if it was, then the rna polymerase wouldn't be able to bind.

01:48 So the two conditions for the lack operon to be on is that the glucose must be low and lactose must be high.

01:57 How does the cell know that glucose is low and lactose is high? well, glucose prevents the production of camp, which is cyclic adenosin monophosphate.

02:10 Okay, camp binds to the cap protein.

02:15 The cap protein stands for cetabolite activator protein, i believe.

02:20 So the camp binds to the cap protein, and then that activates the cap protein.

02:26 Protein to bind to the dna and promote transcription.

02:32 So when glucose is low, there is not enough glucose to block the production of the camp...

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