Regulation of Gene Expression and Cell Specialization

These flashcards cover key vocabulary terms related to gene expression regulation and cell specialization.

Gene Expression Regulation

The ability of prokaryotes and eukaryotes to turn genes on or off based on environmental and internal cues.

Operon

A group of genes that can be turned on or off, comprising a promoter, operator, and genes coding for related enzymes.

Promoter

The site where RNA polymerase attaches to initiate transcription.

Operator

The on/off switch within an operon that regulates transcription.

Repressible Operon

An operon that is usually active but can be repressed when necessary, such as the trp operon.

Inducible Operon

An operon that is usually inactive and can be induced to turn on, such as the lac operon.

Allosteric Activator

A substance that binds to an enzyme and stabilizes its active form, allowing the active sites to remain open.

Allosteric Inhibitor

A substance that binds to an enzyme and stabilizes its inactive form, closing the active sites.

Tryptophan

An amino acid whose presence activates the trp repressor, turning off transcription in the trp operon.

Lactase

An enzyme that digests lactose, controlled by the lac operon.

Differential Gene Expression

The variation in genes expressed in different cell types, determining their phenotype.

Epigenetic Inheritance

Heritable changes in gene expression caused by chromatin modifications that do not alter the DNA sequence.

Cytoplasmic Determinants

Substances in the maternal egg that influence cellular development and differentiation.

Apoptosis

Programmed cell death that allows structures to take shape during development.

Ubiquitin

A small protein that marks unwanted proteins for degradation in proteasomes.

Histone Acetylation

Adds acetyl to histones, makes it looser=more accessible

DNA methylation

adds methyl to DNA, makes it more condensed=less accessible

Control Elements

Segments of non-coding DNA that are binding sites. If an activator binds, gene expression for that segment increases. If a repressor binds gene expression decreases

Alternative splicing

removing certain combinations of introns to make different proteins from a single gene by producing multiple mRNA variants.

initiation factors

microRNA and siRNA bind to mRNA and degrade or block translation

TRP operon

repressible operon- when excess tryptophan binds to the trp repressor, it binds to the operator of the gene and turns off transcription

Lac operon

a inducible operon- when lactose is present, it binds to the lac repressor and turns off the repressor, allowing for the metabolism of lactose by transcribing mRNA for enzymes like β-galactosidase.

prions=

misfolded proteins that cause other proteins to misfold- forms aggregates that can lead to neurodegenerative disease

snRNP

small nuclear RNA- forms spliceosome to recognize, excise, and remove introns (non-coding regions) from pre-mRNA and ligate exons to form mature mRNA

aminoacyl tRNA sythetase

attaches amino acids to tRNA

polyadenylation signal

releases pre-mrna from the DNA in transcription