Epigenetic Control
What is a nucleosome?
Histone octamer, DNA wrapped twice around the histones.
What is the difference between enhancers and promoters?
Promoters bind basal TF's, enhancers bind regulatory TF's. If available promoters constantly bound.
What is alternative splicing? What is the purpose?
Splicing exons together differentially. Purpose of this is to increase number of products that can be produced from limited # of genes.
List 2 ways that translation can be inhibited.
1. RISC complexes
2. modification of ribosomes
3. binding of mRNA by proteins
What is a proto-oncogene? What is an example of this?
A normal gene that if mutated can cause cancer (uncontrolled cell growth/division). RAS Protein.
What is the normal structure of inactive chromatin?
30 nm fiber.
What allows transcription to initiate once all transcription factors bound?
Mediator complex
What contributes to mRNA stability? Why is it important to degrade them after a time?
5' cap and Poly A tail. Constant production of all products would not allow for adaptation to occur.
What are 3 modifications that make a protein functional?
1. glycosylation
2. cleavage
3. proper folding
4. phosphorylation
5. Association of ions
6.
What is p53? What does it do?
It is a regulatory transcription factor. Activates genes that arrest cell, DNA repair and apoptosis.
What do DNA methylation and histone acetylation do in terms of transcription? Where is DNA methylated?
DNA methylation=Transcriptionally inactive
Histone acetylation=transcriptionally active
DNA methylated at CG sequences.
What do pioneer transcription factors do?
In RNA interference what binds to the mRNA? Once it binds what happens?
miRNA (single stranded) binds to mRNA. If perfect match RISC cuts the RNA, if not perfect match holds it to interfere with translation.
What are 3 ways to change a protein from inactive to active?
- Phosphorylation
- association with ions
- association with other protiens
Lots of options here.
Mutation that changes it to perpetually inactive. Changes the active site so can't recognize the correct DNA sequence. Mutation in enhancer that stops p53 from being transcribed.
Transgenerational epigenetic modifications are rare, but what is one way discussed in class that they can occur?
Vinclozolin exposure administered to a pregnant female.
How are regulatory transcription factors activated and how to they recognize specific DNA sequences?
Can be activated through signaling pathways, can be phosphorylation, association with lipid soluble hormones, association with activated proteins. Have specific amino acid sequences that can associate with specific DNA sequences.
Where on the mRNA does the RISC complex bind?
Where in the cell do glycosylations get added/trimmed?
RER, golgi apparatus.
What 2 factors lead to differential gene expression among different bodily tissues?
They contain different epigenetic modifications, and have different transcription factors.
Where are miRNA's encoded? What form do they take on after they have been transcribed?
GENES!!!! Hairpin.