Control of Gene Expression

These flashcards cover key concepts regarding gene expression and its regulation in prokaryotic and eukaryotic cells, based on the lecture notes.

What is gene expression?

The overall process that includes transcription and translation, whereby the information in a gene is used to make a protein.

What process involves copying DNA to make RNA?

Transcription.

What process involves reading mRNA to make a polypeptide?

Translation.

What are the major steps required for gene expression?

Transcription, translation, and regulation of these processes.

Why is regulation of gene expression critical in cells?

To ensure that cells produce only the proteins necessary for their current conditions and needs.

What is the operon system?

A system in prokaryotic cells that allows for the regulation of gene expression, often involving a promoter, operator, and regulatory genes.

When would the lac operon be turned on?

When lactose is present in the environment.

What happens to the repressor protein in the lac operon when lactose binds to it?

It becomes inactive, allowing transcription to occur.

What is an inducible operon?

A type of operon that is turned on by the presence of a molecule, such as lactose in the lac operon.

What is the trp operon?

A repression-type operon in bacteria that is turned off in the presence of tryptophan.

What happens to the trp operon when tryptophan is present?

The repressor protein is activated and binds to the operator, preventing transcription.

What is alternative splicing?

A process that allows a single gene to produce multiple proteins by splicing RNA in different ways.

Why is alternative splicing beneficial to cells?

It increases the variety of proteins that can be produced, allowing for greater functional diversity.

What is the role of histones in gene regulation?

Histones help package DNA tightly, making it inaccessible for transcription when DNA is wrapped around them.

What is a transcription complex?

A assembly of proteins that helps RNA polymerase bind to the promoter, initiating transcription.

What are enhancers in the context of gene expression?

DNA sequences that help regulate transcription by binding activator proteins to assist the formation of the transcription complex.

What is meant by 'chromosome inactivation'?

A process where one chromosome of a pair is randomly inactivated, preventing its genes from being expressed.

How does the presence of lactose affect the lac operon?

It induces the operon to turn on, allowing genes to be transcribed for lactose breakdown.

What is feedback regulation in the context of the lac operon?

The process by which the presence of lactose turns on the operon, and the depletion of lactose shuts it off.