Gene Regulation

These flashcards cover key concepts in gene regulation as outlined in the lecture notes.

What causes the lac operon to be inactive in the absence of lactose?

A repressor protein binds to a specific site in the lac operon.

What happens to the lac operon when lactose is present?

Lactose binds to the repressor protein, causing it to dissociate from the binding site.

How does glucose affect the transcription of the lac operon?

In the absence of glucose, cAMP accumulates and activates CAP, which enhances transcription.

What are the three parts of an operon model?

Promoter, Operator, Structural Genes.

What is the role of a repressor in gene regulation?

A repressor blocks RNA polymerase binding, preventing transcription.

What is the difference between polycistronic and monocistronic genes?

Polycistronic genes have one switch for multiple genes, while monocistronic genes have a separate switch for each gene.

What type of operon is typically ON but can be repressed?

Repressible operons.

What is an example of a repressible operon?

The TRP operon, which produces enzymes for the synthesis of tryptophan.

What type of operon is typically OFF but can be induced?

Inducible operons.

What is an example of an inducible operon?

The LAC operon, which codes for enzymes to break down lactose.

What role does acetylation play in eukaryotic gene expression?

It turns on DNA by loosening the coiling around histones.

What is alternative splicing?

A process that can yield different proteins from the same pre-mRNA due to different processing.

What is the enzyme responsible for binding to the promoter to start transcription?

RNA polymerase.

What is the function of enhancers in transcriptional control?

They are distant genes that speed up transcription or make it more frequent.

What accounts for the size of patches in calico cats?

The timing of the inactivation of the X chromosome.

What occurs during post-translational control?

Proteins can be made in an inactive form or need modification before they are complete.