Prokaryotic Gene Regulation in Bacteria

These flashcards cover the key concepts of prokaryotic gene regulation, specifically focusing on the lac operon, roles of operons, and CRISPR-Cas immunity in bacteria, facilitating a better understanding of the lecture material.

What are the types of genetic regulation in bacteria?

Constitutive, Inducible, and Repressible.

Why is differential gene expression beneficial for cells?

It conserves resources and saves energy, prioritizing necessary gene products.

What is constitutive gene regulation?

A type of gene regulation where the gene is always expressed.

What is inducible gene regulation?

A type of gene regulation where the gene is expressed in response to some stimulus.

What is repressible gene regulation?

A type of gene regulation where the gene is repressed (not expressed) in response to some stimulus.

What is the role of an activator protein in gene regulation?

It binds to DNA and increases transcription.

What is the role of a repressor protein in gene regulation?

It binds to DNA and decreases transcription.

In the lac operon, what does LacZ do?

LacZ encodes β-galactosidase, which breaks down lactose.

What happens to the lac operon in the presence of lactose?

Lactose binds to the LacI repressor, preventing it from binding to the operator, allowing transcription.

How does CAP affect lac operon expression when glucose is absent?

cAMP binds to CAP, allowing it to bind to the lac operon promoter and induce expression.

What is the function of CRISPR in bacteria?

Provides adaptive immunity by incorporating viral DNA into a bacterial chromosome.

How is crRNA related to CRISPR-Cas immunity?

It contains a spacer and repeat sequence and guides Cas proteins to cut target DNA.

What occurs when a bacterium's spacer sequence is deleted at the CRISPR locus?

The bacterium would lose its adaptive immunity to the corresponding phage.

What occurs when glucose is present for E. coli and lactose is also available?

Lac gene expression is low due to lack of cAMP and CAP binding to the promoter.

What genetic mutations can affect the expression of the lac operon?

Mutations such as lacZ-, lacY-, lacI-, and lacOC can impact operon expression under varying conditions.

What occurs to transcription when lactose is absent in E. coli?

The repressor binds to the operator, blocking transcription.

What are the steps of the CRISPR immunity process?

Acquisition of viral DNA, transcription into crRNA, and target interference via Cas cutting DNA.

What happens to lac operon expression when only glucose is present?

Lac gene expression is very low as CAP cannot bind to the promoter.