HLSC322 exam 3 review

Front

What is the lac operon?

Back

The lac operon is a set of genes in E. coli that are involved in the metabolism of lactose. It is regulated by the presence or absence of lactose and glucose.

Front

What is the function of the LacZ enzyme?

Back

LacZ is an enzyme that breaks down lactose into glucose and galactose, allowing E. coli to utilize lactose as an energy source.

Front

What happens to the lac operon when glucose is present?

Back

When glucose is present, the lac operon is repressed, and the genes for lactose metabolism are not expressed.

Front

Define negative regulation in the context of operons.

Back

Negative regulation occurs when a repressor protein binds to the operator region of an operon, preventing transcription of the associated genes.

Front

What is the role of the repressor in the lac operon?

Back

The repressor binds to the operator region of the lac operon in the absence of lactose, blocking RNA polymerase from transcribing the genes.

Front

What is the significance of the Trp operon?

Back

The Trp operon is involved in the biosynthesis of tryptophan and is an example of a negative repressible operon.

Front

How does lactose affect the lac operon?

Back

Lactose acts as an inducer by binding to the repressor, causing it to release from the operator and allowing transcription of the lac genes.

Front

What is positive regulation in operons?

Back

Positive regulation involves an activator protein that enhances the transcription of genes when bound to a specific site on the DNA.

Front

Explain the concept of operon.

Back

An operon is a cluster of genes under the control of a single promoter, allowing coordinated regulation of gene expression.

Front

What is the difference between inducible and repressible operons?

Back

Inducible operons are activated by the presence of a substrate (inducer), while repressible operons are inhibited by the end product of the pathway.