Xeu Genetic Regulation and the Lac Operon

Genetic Regulation

Control of gene expression in cells.

Cost of Protein Synthesis

22 amino acids per second during translation.

Regulation Goal

Produce correct protein amounts at any step.

Constitutive Genes

Gene products needed continuously, except during M phase.

Lac Operon

Example of genetic regulation in E. coli.

Operon

Multiple coding regions controlled by one promoter.

Beta Galactosidase

Lac operon product that breaks lactose glycosidic bonds.

Galactoside Permease

Protein facilitating lactose entry into the cell.

Transcription Initiation

Primary regulation point for the lac operon.

Lac I

Gene coding for the repressor protein, always expressed.

Repressor Protein

Binds to operator, inhibiting transcription.

Negative Regulation

Low beta galactosidase when lactose is absent.

Positive Regulation

Lactose removes repressor, allowing transcription.

Regulatory Examples

Methods include mRNA degradation and protein activity control.

Lac Y

Gene coding for galactoside permease in lac operon.

Lac Z

Gene coding for beta galactosidase in lac operon.