Biology Week 9 Lecture 22: Eukaryotic Gene Expression Regulation

Vocabulary flashcards covering eukaryotic gene regulation mechanisms, including epigenetic modifications, transcription factors, alternative splicing, microRNAs, and post-translational degradation.

Epigenetics

Heritable or environmental modifications directly to DNA or histones that regulate transcription without altering the underlying nucleotide sequence.

DNA Methylation

An epigenetic modification involving the direct addition of a methyl group to DNA, which typically turns transcription off by condensing DNA or physically blocking transcription factors and RNA polymerase.

Histone Acetylation and Phosphorylation

Epigenetic modifications added to histone tails that signal the DNA to unwind from histones, allowing RNA polymerase access to the promoter to increase or activate transcription.

Cortisol

A stress hormone that induces epigenetic modifications to histone tails, which can inhibit the transcription of genes needed to fight off pathogens.

Transcription Factors

Proteins that regulate transcription by binding to regulatory regions of DNA to help recruit RNA polymerase to the promoter.

FACT Complex

A cellular complex that assists in unwinding eukaryotic DNA from histones to enable transcription to occur.

Enhancers

DNA regulatory regions located up to 1,000 base pairs away from the promoter that bind transcription factors or activators to increase transcription.

Mediator Proteins

Proteins that facilitate the bending and changing of DNA shape to bring distant enhancer regions into close contact with the promoter.

Eukaryotic Repressors

Proteins that block transcription by binding to promoters or enhancers to prevent transcription factors and RNA polymerase from binding.

Alternative Splicing

A post-transcriptional mechanism where different combinations of exons from a single pre-mRNA are joined into mature mRNA, producing distinct functional protein variants.

MicroRNAs (miRNAs)

Small non-coding RNA molecules that bind complementarily to target messenger RNAs, physically blocking the ribosome and signaling the mRNA for degradation.

RISC Complex

A protein complex that works with microRNAs to pair with complementary target mRNAs to block translation and degrade the transcript.

eIF-2 (Initiation Factor 2)

A translation initiation protein that binds the initiator tRNA carrying methionine and helps recruit mRNA to the small ribosomal subunit; it is inactivated when phosphorylated.

Ubiquitin

A molecular protein tag attached to unneeded proteins to mark them for destruction.

Proteasome

A protein complex that recognizes ubiquitin-tagged proteins and degrades them into small peptides and amino acids.