How does cap increase transcription of the lac operon?

How does cap increase transcription of the lac operon?

As it turns out, RNA polymerase alone does not bind very well to the lac operon promoter. The cAMP attaches to CAP, allowing it to bind DNA. CAP helps RNA polymerase bind to the promoter, resulting in high levels of transcription.

What role do cAMP and cap play in transcription of lac operon genes?

What role do cAMP and CAP play in transcription of lac operon genes? A) CAP binds the CAP binding site of the lac promoter to carry out negative control of operon gene transcription, whereas cAMP blocks the CAP binding site and thereby allows fine-tuning of the system.

Is the cap cAMP effect on the transcription of the lac operon An example of positive or negative regulation Why?

The lac operon is a typical inducible operon. As mentioned previously, E. coli is able to use other sugars as energy sources when glucose concentrations are low. To do so, the cAMP–CAP protein complex serves as a positive regulator to induce transcription.

How would transcription of the lac operon be affected if a mutation in the operator sequence prevented the repressor from binding to it?

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 happens if the operator is mutated?

What happens if there is a mutation observed in the operator gene in the lac operon? if the repressor binds more strongly, there would be less transcription. if the repressor has difficulty binding then it is possible that the operon would be turned on when not needed.

What do promoters do?

​Promoter. A promoter is a sequence of DNA needed to turn a gene on or off. The process of transcription is initiated at the promoter. Usually found near the beginning of a gene, the promoter has a binding site for the enzyme used to make a messenger RNA (mRNA) molecule.

What is the cap site for the lac operon?

cAMP/CRP complex binds to a specific sequence in the lac control region called the “CAP” site. The CAP site is just upstream from the RNA polymerase binding site. Mutations in the CAP site that prevent cAMP-CRP binding also prevent high levels of expression of the lac operon….

What do you mean by nutrient repression?

Abstract. Catabolite repression collectively describes the reversible process by which during rapid catabolism of one carbon source, uptake and catabolism of poorer substrates is prevented.

Under which conditions does the catabolite activator protein become active?

When glucose levels decline in the cell, accumulating cAMP binds to the positive regulator catabolite activator protein (CAP), a protein that binds to the promoters of operons that control the processing of alternative sugars, such as the lac operon….

Is cap an activator?

The catabolite activator protein (CAP, also known as cAMP receptor protein, CRP) is a transcriptional activator, present as homodimer in solution, each subunit including a ligand-binding domain at the N-terminus and a DNA-binding domain at the C-terminus.

What does the catabolite activator protein do?

Catabolite activator protein (CAP), also known as cyclic AMP receptor protein (CRP), is activated by cyclic AMP and stimulates synthesis of the enzymes that break down non-glucose food molecules.

What is the difference between an activator and an inducer?

In molecular biology, an inducer is a molecule that regulates gene expression. Activators generally bind poorly to activator DNA sequences unless an inducer is present. Activator binds to an inducer and the complex binds to the activation sequence and activates target gene. Removing the inducer stops transcription.