Gene Expression and Regulation in Eukaryotes Flashcards
What is the principal difference between regulation of transcription in eukaryotes and prokaryotes?
In eukaryotes, the ground state is that heterochromatin is off - gene is not open to RNA pol II. The heterochromatin has to remodel to facilitate RNA pol II to be active.
How is regulation controlled in eukaryotes?
Remodeling unwinds the heterochromatin to expose the promoter region for transcription.
Histone acetylation usually leads to
Activation
Histone methylation usually leads to
Supression
What do enhanceosomes recruit?
Chromatin remodelers
What does the ehanceosome form a binding site for? And what does it do?
GCN 5 complex binds to enhanceosome and adds acetyl groups to nuc 1 and 2
The acteylation of the nucleosomes exposes the TATA box, what happens next?
TATA binding protein (TBP) binds to the TATA box which allows transcription to begin
What is gene silencing caused by?
The spread of heterochromatin
How do you stop the spread of heterochromatin?
Barrier insulater between heterochromatin and euchromatin?
How does the barrier insulator work?
Barrier insulator attracts HAT protein which removes methylation on surrounding histone tails and acetylates the histone tails on either side causing inactivation
How are the 2 X chromosomes in females regulated?
The first gene to bind to protein YY1 in the vicinity of a bound PRC2 will be inactivated and the other X chromosome will be inactivated.
What is a UAS sequence in galactose genes?
Binding sites for activator self-expression protein
What is a UAS sequence in galactose genes?
Binding sites for activator self-expression protein
the Gal4 has what 3 domains?
Activation domain
dimerization domain
DNA-binding domain
What does the DNA binding domain do?
Binds to the upstream regulatory sequences of the genes
What does the activation domain do?
Attracts DNA polymerase and regulatory components and starts expression of the gene
How can Gal4 regulate genes on separate chromosomes?
When Gal4 is expressed in the cell, it can bind to all UAS sequences in the cell
If Gal80 protein is bound to the activation domain of Gal4?
What causes it to dissociate?
The gene is still inactive wil Gal80 is bound?
Gal80 will disociate in the presence of galactose and Gal3 and the gene will be actively expressed
Port-translational Regulation
What does the RISC complex do?
- Prevent Cap binding
- Interefere with elongation
- Prevent Ribosome assembly
- Remove poly A tail
How do transcription factors control yeast sex?
Depending on what transcription factors are bound, they will deteremine what sex the yeast is
How is yeast mating type controlled by recombination?
MATa active - a mating type
HMLalpha is copied into MATalpha locus- alpha mating type
HMRa is copied into MATalpha locus - a mating type
Enhabcer-blocking insulator place holder
Maternal mitochondria inhertance
What results in conflict?
Biparental inhertiance - conflict
Uniparental inhertiance - no clonflict
