Gene Regulation Lecture Notes

Flashcards covering gene regulation in prokaryotes and eukaryotes, operons, transcription, and translation.

What is gene regulation?

Control of the level of gene expression, involving controlling whether a gene is actively expressed or inactive.

What are constitutive genes?

Also known as housekeeping genes, they are always active because they are essential for cell survival.

At what three levels does regulation of gene expression occur in prokaryotes?

Transcription, translation, and after a protein has been synthesized.

What is an operon?

In prokaryotes, genes are clustered in a region under the control of a single promoter; this region is called an operon.

What components are in the regulatory region of the lac operon?

Promoter, operator, and CAP binding site.

How does lactose act as an inducer?

By removing the repressor and inducing (leading to) transcription.

What is the role of cAMP in the context of the lac operon?

cAMP binds to the activator protein CAP (Catabolite activator protein); together they will bind to DNA ahead of the promoter to help RNAP bind, increasing transcription.

Under what conditions will cAMP activated CAP proteins stimulate transcription of the lac operon?

When glucose levels are low.

What is the function of the trp operon?

Codes for the production of the amino acid tryptophan.

What regulatory region does the trp operon contain?

A promoter and an operator.

Name the different levels of gene regulation in eukaryotes.

Chromatin remodeling, transcriptional, RNA processing (post-transcriptional), mRNA stability, translational, and post-translational.

What is the function of activator molecules in transcription?

Activator molecules bind to DNA upstream from a gene’s promoter region, causing the DNA to uncoil and expose the promoter region or TATA box.

What modifications must mRNA get before it can exit the nucleus?

A modified 5’ guanine cap and a polyadenine tail.

How does alternative splicing increase protein diversity?

Variations in a gene can be determined by cutting out various introns from the pre-mRNA and splicing together the exons.

How do the 5’ cap and poly A tail affect mRNA stability?

They allow for the mRNA to last longer in the cytosol by protecting the mRNA that needs to be translated.

How can regulatory proteins prevent translation?

Regulatory proteins attach to the mRNA and prevent the ribosomal subunits from binding to the mRNA, preventing translation from occurring.

What post-translational modifications are often needed for proteins?

Synthesized proteins need to be folded and assembled; often proteins need some small chemical change to activate them.