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How does breakdown of glucose inhibit transcription of the lac operon?

(a) Under conditions of high glucose, a glucose breakdown product inhibits the enzyme adenylate cyclase, preventing the conversion of (more…) Glucose control is accomplished because a glucose breakdown product inhibits formation of the CAP-cAMP complex required for RNA polymerase to attach at the lac promoter site.

How does breakdown of glucose inhibit transcription of the lac operon quizlet?

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 is the lac operon inhibited?

The lac repressor is a protein that represses (inhibits) transcription of the lac operon. It does this by binding to the operator, which partially overlaps with the promoter. When lactose is not available, the lac repressor binds tightly to the operator, preventing transcription by RNA polymerase.

How does glucose repress the expression of the lac operon?

how does glucose repress the expression of the lac operon ? the presence of glucose in the environment inhibits the production of cAMP, thereby preventing the binding of CAP to the DNA.

Which Lac mutant is called the super repressor?

And furthermore no lac Z around to metabolize it. LacIs = “super-repressor” can bind operator even when lactose is bound. A gain-of-function allele. II. Additional level of control: Catabolite activator protein.

Is lac operon constitutive?

The lacI gene coding for the repressor lies nearby the lac operon and is always expressed (constitutive). Thus altered, the repressor is unable to bind to the operator, allowing RNAP to transcribe the lac genes and thereby leading to higher levels of the encoded proteins.

What happens if lacI is mutated?

A mutation in the lacI gene results in the expression of β-galactosidase. In addition to galactose and X-gal, β-galactosidase can also cleave P-gal. This results in the production of galactose, which can provide a sole carbon source, thus permitting the growth of bacterial colonies.

What does OC mean in lac operon?

Oc mutants are changes in the DNA sequence of the operator that impair the. binding of the lac repressor. Therefore, the lac operon associated with the Oc operator cannot be turned off. Because an operator controls only the genes on the same DNA strand, it is cis (on the same strand) and dominant (cannot be turned off) …

What would happen if the operator was removed from the lac operon?

According to the lac operon model proposed by Jacob and Monod, what is predicted to occur if the operator is removed from the operon? The lac operon would be transcribed constitutively. CAP bound to the CAP binding site increases the frequency of transcription initiation.

What is the function of an inducer?

In molecular biology, an inducer is a molecule that regulates gene expression. An inducer functions in two ways; namely: By disabling repressors. The gene is expressed because an inducer binds to the repressor.

What does the inducer bind to in the lac operon quizlet?

In the case of the lac operon, lactose is the inducer. If lactose is present, it binds to and inactivates the repressor by causing it to fall off the operator. If lactose operator is free of repressor, then RNA Polymerase is able to bind. The operon is induced when lactose molecules bind to the repressor protein.

What does the lac operon code for?

The lac, or lactose, operon is found in E. coli and some other enteric bacteria. This operon contains genes coding for proteins in charge of transporting lactose into the cytosol and digesting it into glucose. This glucose is then used to make energy.

What is the basic function of the lac operon quizlet?

What is the basic function of the lac operon? A- To code for enzymes involved in synthesizing lactose.

What is the function of the lac operator quizlet?

What is the function of the lac operator? It produces the lac repressor protein.

Which type of mutation leads to a frameshift mutation quizlet?

A frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (insertions or deletions) of a number of nucleotides in a DNA sequence that is not divisible by three.

What is the function of the lac repressor system in E coli?

The Lac repressor protein, LacI, prevents the transcription of genes involved in lactose utilization (lac genes) in E. coli. Like many other repressors, LacI utilizes multiple operators to increase the efficiency of repression.

How many structural genes are in the lac operon?

three genes

What is operon model of gene expression?

The operon model of prokaryotic gene regulation was proposed by Fancois Jacob and Jacques Monod. Groups of genes coding for related proteins are arranged in units known as operons. An operon consists of an operator, promoter, regulator, and structural genes. If the repressor protein is removed, transcription may occur.

What are two functions of gene regulatory proteins?

Most of the known phosphorylated response regulators employ the two-component system to stimulate or repress the transcription of specific targetted genes. Allosteric regulatory proteins bring about the alteration of metabolic pathways by utilizing end product repression, enzyme induction, and catabolite repression.