Unit 5 Quiz 3

Prokaryotic Genome Structure

Singular circular chromosome, contains little non-coding DNA.

Eukaryotic Genome Structure

Multiple long strands of chromosomes, contains significant amounts of non-coding DNA.

Gene Expression Control in Eukaryotes

Control can occur during transcription, post-transcriptional modification, translation, and post-translation.

Operon

A cluster of genes in prokaryotes that can be turned on or off to regulate transcription and protein production.

Common Features of Operons

Includes an operator, repressor protein, co-repressor/coreducer, promoter, regulator, and structural genes.

Function of the Operator in an Operon

The operator is the binding site for the repressor protein, which can inhibit transcription when bound.

Role of the Repressor Protein

When active, the repressor binds to the operator to prevent transcription.

Corepressor and Coreducer Function

Corepressors activate repressor proteins to inhibit transcription; coreducers deactivate them to allow transcription.

Tryptophan Control in Bacteria

The trp operon regulates tryptophan production, functioning as a repressible operon to prevent waste when enough is produced.

Tryptophan Feedback Inhibition

Occurs in the trp operon where excess tryptophan binds as a corepressor to halt transcription, preventing overproduction.

Glucose and Lactose Relationship

Lactose can be broken down by bacteria into glucose for energy.

Function of B-galactosidase

An enzyme that breaks lactose into allolactose and glucose.

Lac Operon and Breakdown of Lactose

Controls the breakdown of lactose and is considered inducible because it is activated in the presence of lactose.