Gene Expression and Regulation in Prokaryotes and Eukaryotes

Flashcards covering key concepts in gene expression and regulation for prokaryotes and eukaryotes.

What is gene expression and regulation?

The controlling of the production of certain proteins, determining which proteins need to be produced and when.

Why do prokaryotes regulate their genes?

1) To conserve energy 2) To conserve materials.

What is an operon?

An operon is made up of a promoter and a series of two or more genes that make enzymes for a specific metabolic pathway.

How do prokaryotes regulate genes?

Prokaryotes use operons to control gene expression.

What characterizes repressible operons, such as the trp operon?

Repressible operons are usually in the 'on' position but turn 'off' when too much of a product is made.

What characterizes inducible operons, such as the lac operon?

Inducible operons are usually 'off' but are turned 'on' when a certain molecule becomes present.

What are the three major ways eukaryote genes are regulated?

1) Pre-transcription (chromatin level) 2) Transcription (protein synthesis) 3) Post-transcription (degradation/enzyme control).

What is the role of activator proteins in transcription regulation?

Activator proteins bind to enhancer control elements and help form an active initiation complex with RNA Polymerase II.

What is histone acetylation and its effect on chromatin?

The addition of an acetyl group to a histone tail decondenses heterochromatin to euchromatin, allowing gene expression.

What is DNA methylation and its effect on gene expression?

The addition of a methyl group to DNA bases causes condensing of DNA, leading to reduced gene expression; removal of methyl groups can resume expression.

What is alternative splicing?

Alternative splicing allows different combinations of exons to be joined together to produce different proteins from the same gene.

What influences methylation patterns in epigenetic inheritance?

Environmental factors can influence methylation patterns, and these patterns can be passed to future generations.

What happens to proteins marked with ubiquitin?

Proteins marked with ubiquitin are targeted for degradation by proteases.