Bacterial Gene Regulation and Eukaryotic Gene Expression

Flashcards for reviewing key concepts in bacterial gene regulation (lac operon) and eukaryotic gene expression.

Gene expression

The process by which information in a gene is made into a functional product, such as a protein or RNA.

Gene regulation

The ability of a cell to control the expression of their genes and gene products.

Metabolic Control

Cells cope with environmental fluctuations by exerting metabolic control mainly by varying enzyme concentration, regulating protein synthesis and adjusting the activity of enzymes already present.

Transcriptional Regulation

Increasing or decreasing the rate of transcription.

b-galactosidase

Enzyme that breaks down Lactose (milk sugar) to glucose and galactose

Operon

A unit of genetic material consisting of related genes, promoter, and operator, that functions in bacteria.

Inducible Operon

Operon that is usually 'off' but can be stimulated ('turned on') to be transcribed.

lacZ

Gene that encodes B-galactosidase.

lacY

Gene that encodes galactoside permease.

lacA

Gene that encodes B-gal transacetylase.

lac Promoter (P)

RNA polymerase binding site.

lac Operator (O)

Region of DNA in between lac promoter and start of lacZ; binding site for the repressor protein.

lacI

Gene that encodes lac repressor, a protein with two binding interfaces: one that can bind DNA of the operator, and one that can bind lactose.

Allolactose

Isomer of lactose, binds to the repressor, changes its shape and thus inactivates it.

Catabolite Activator Protein (CAP)

Activated by cAMP accumulates, which binds the promoter and stimulates transcription of Lac operon.

Positive gene regulation

Catabolite repression.Insures that the lac operon is turned on by the presence of lactose but only in the absence of glucose

Induction

When transcription increases in response to the presence of a specific signal.

Inducers

Small molecules that stimulate induction.

Repression

When transcription decreases in response to the presence of a specific signal.

Housekeeping genes

Genes that control routine functions common to all cells.

Differential gene expression

Selective expression of different genes by cells with the same genome.

DNA methylation

Generally reduces transcription.

Histone acetylation

Loosens chromatin structure, enhancing transcription.

Epigenetics

Heritable traits that do not involve changes in DNA sequence.

Histone deacetylation

Removal of acetyl groups on histone lysines allows histones to wrap around DNA more tightly, decreases transcription.

Activator

Protein that binds to an enhancer and stimulates transcription of a gene.

Cytoplasmic determinants

Maternal substances (RNA, proteins) in the egg that influence early development.

Inductive Signals

Signal molecules that diffuse from embryonic cells cause transcriptional changes in nearby target cells.

MyoD

Transcription factor that binds to enhancers of various target genes to produce muscle-specific proteins and form skeletal muscle cells.

Ubiquitylation

Process that attaches ubiquitin to a lysine residue on a substrate protein,signaling their degradation via the proteasome.

Proteasomes

Giant protein complexes that bind protein molecules and degrade them.