Regulation of Gene Expression

Front

What is the main requirement of bacterial gene regulation?

Back

Production of enzymes and other proteins when needed.

Front

What are the three steps involved in gene expression?

Back

1. Transcribing the gene to form mRNA 2. Translating mRNA into protein 3. Activating the protein

Front

What is an operon?

Back

A gene complex consisting of a group of structural genes with related functions plus the closely linked DNA sequences responsible for controlling them.

Front

Who first proposed the operon model?

Back

Francois Jacob and Jacques Monod in 1961.

Front

What are the basic components of an operon?

Back

1. Regulatory gene 2. Promoter 3. Operator 4. Structural genes

Front

What is the role of the repressor protein in an operon?

Back

It controls whether the operon is active or not.

Front

What is the difference between a repressible operon and an inducible operon?

Back

A repressible operon is usually ON but can be inhibited, while an inducible operon is usually OFF but can be stimulated.

Front

What happens to the trp operon when tryptophan is absent?

Back

The repressor is unable to attach to the operator, allowing RNA polymerase to bind and enzymes for tryptophan synthesis to be produced.

Front

What happens to the trp operon when tryptophan is present?

Back

Tryptophan binds to the repressor protein, making it functional, which blocks the synthesis of enzymes for tryptophan synthesis.

Front

What is the lac operon?

Back

An operon that is usually OFF but can be stimulated when lactose interacts with a regulatory protein.