Unit 4 - Ch. 17: Genetic Regulation in Eukaryotes Flashcards
Why is gene regulation more complex in eukaryotes?
Because of multicellularity, specialized cells, and larger genomes
What are the two types of transcription factors?
- General TFs: required for all transcription
- Regulatory TFs: increase/decrease transcription
What do activators and repressors bind to?
- Activators → Enhancers
- Repressors → Silencers
What are the 3 ways to modulate regulatory transcription factors (RTFs)?
- Effector molecules (e.g.hormones)
- Protein-protein interactions
- Covalent modifications
How do steroid hormones affect transcription?
Bind intracellular receptors → form homodimers → activate gene expression via GREs
What is chromatin remodeling?
Changing nucleosome position or histone composition to regulate DNA access
What is the effect of histone acetylation?
Loosens DNA, increases transcription
What is DNA methylation?
Addition of methyl groups (usually to CpG islands) → silences gene
What is a nucleosome-free region (NFR)?
A gap in chromatin (e.g., near promoters) to allow transcription machinery to bind
How is mRNA stability regulated?
Binding proteins and AU-rich elements (AREs) control degradation
What does IRP do in low iron conditions?
- Ferritin mRNA: IRP blocks translation
- Transferrin receptor mRNA: IRP stabilizes mRNA
What happens in high iron conditions?
- IRP is inactive
- Ferritin made (translation ON)
- Transferrin receptor mRNA is degraded
