Chromatin Remodeling

Question 1

Epigenetics

Answer 1

Regulation of gene expression by changes in chromatin structure

Question 2

Heterchromatin

Answer 2

Densely packed

Inactive

Question 3

Euchromatin

Answer 3

Loosely packed

Active

Question 4

Position Effect Variegation

Answer 4

Gene transferred from euchromatic region to heterchromatic region (or vise versa)

Results in altered gene expression

Question 5

HATs

Answer 5

Histone acteyl transferases

		§ Enzymes that transfer acetyl groups to specific lysine residues of histone (i.e. H4) of the nucleosomes Loosens the DNA-histone association and "opens" the chromatin

Question 6

HDACs

Answer 6

Histone deacetylases

Removes acetyl groups

Compacts chromatin

Question 7

SWI/SNF

Answer 7

Shifts nucleosomes along DNA to clear promoter regions for TF binding

Question 8

Dosage Compensation

Answer 8

Mammal
- Random inactivation of one X chromosome

Drosophilia
- One X chromosome in male are hyperactivated

Nematod
- Both X chromosomes are hypoactivated

Question 9

PABPI

Answer 9

molecules bind to the poly(A) tail and interact with initiation factors that bind to the 7-MG cap

Helps with circulization of mRNA

Question 10

Deadenylase

Answer 10

Degrades poly(A) tail, binds to AUUUA in the 3’ UTR region

Deadenylation limits PABPI binding

• Once the poly(A) tail is only 30 nucleotides long, the mRNA is then degraded by either of 2 mechanisms
○ De-capping (7-MG cap removed) and 5’-3’ degradation
Exosome mediated 3’-5’ degradation