Understanding Operons with Amoeba Sisters

Front

What is an operon?

Back

An operon is a cluster of genes under the control of a single promoter, which are transcribed together as a single mRNA molecule.

Front

What is the function of the promoter in an operon?

Back

The promoter is a DNA sequence where RNA polymerase binds to initiate transcription of the operon.

Front

What is the role of the operator in an operon?

Back

The operator is a segment of DNA that a repressor protein can bind to, blocking RNA polymerase and preventing transcription.

Front

What is a repressor protein?

Back

A repressor protein is a regulatory protein that inhibits gene expression by binding to the operator region of an operon.

Front

What is the lac operon?

Back

The lac operon is a set of genes involved in the metabolism of lactose in bacteria, regulated by the presence or absence of lactose.

Front

What is the trp operon?

Back

The trp operon is a set of genes involved in the biosynthesis of tryptophan in bacteria, regulated by the availability of tryptophan.

Front

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

Back

In the presence of lactose, the lac operon is activated, allowing for the transcription of genes needed to metabolize lactose.

Front

What is the difference between inducible and repressible operons?

Back

Inducible operons are activated by the presence of a substrate (like lactose), while repressible operons are inhibited by the presence of a product (like tryptophan).

Front

What is the effect of an active repressor on transcription?

Back

An active repressor binds to the operator, blocking RNA polymerase and preventing transcription of the operon.

Front

What is the role of RNA polymerase in an operon?

Back

RNA polymerase is the enzyme that synthesizes RNA from the DNA template during transcription.