Epigenetics

Question 1

What’s the different developmental potential? What is the function of epigenetic mechanism?

Answer 1

Totipotent, pluripotent, multipotent, unipotent. Underly the stage specific gene activation and repression during development

Question 2

whAT IS THE REPLICATION TIMING FOR REPRESSED AND EXPRESSED CELLS LIKE?

Answer 2

Repressed genes it is in late S phase while expressed genes it happens in the early S phase

Question 3

What is the nuclear location like for silenced and activated genes?

Answer 3

Silenced genes are in the periphary of the nucleus while expressed genes are in the centre.

Question 4

What is the nucleosome made up of?

Answer 4

Histone octamer-2x(H2A,H2B, H3 and H4) AND 147 bp is wrapped around it 1.7 times. It has a linker:H1

Question 5

What is epigenetic?

Answer 5

It’s any inheritable influence on gene activity that occurs but doesn’t involve changing DNA sequence. It affects expression in a regional and cell specific manner

Question 6

What are the names of the different chromosome structures associated with the trasncriptional states?

Answer 6

Heterochromatin-silenced or repressed

euchromatin

Question 7

What is the histone coding hypothesis?

Answer 7

It’s the position and composition of the modifications that occur in the histone tails collectively they will determine the transcription state by recruiting chromatin modifying proteins that will recruit or stop transcription factors from acting on their designated spots.

Question 8

What is H3K4 methylation associated with?

Answer 8

Gene activation

Question 9

What is H3K27 an H3K9 methylation associated with? What protein is involved in the process?

Answer 9

Silencing.

HP1

Question 10

Outline the general steps involved in transcribing chromatin

Answer 10

1. Covalently modify the histone tails
2. Nucleosomes move away from the promoter in an ATP dependent manner
3. CO-activators and other complexes are recruited

Question 11

What histone remodelling enzyme is associated with repression?

Answer 11

HIstone deacetylase

Question 12

Are CpG islands methylated? And what are they and what is their gene state?

Answer 12

Usually not only in imprinted genes and inactive x, they are CG rich sequence near promoters and they’re genes are silenced

Question 13

Where does methylation occur? Gene state

Answer 13

CG regions, silenced

Question 14

How is methylation reversed?

Answer 14

Through oxidation, 3 oxidation states via TET

Question 15

How is DNA methylation altered in cancer?

Answer 15

The promoters of the tumour suppressors are methylated repeats including transposons are hypomethylated.
Also HAT and HDAC are frequently mutated in cancer

Question 16

How can these epigenetic changes be targeted?

Answer 16

They can use inhibitors against chromatin remodelling protein such as PRC2 if it methylated tumour suppressor genes

Question 17

What is 5mC?

Answer 17

Long term heritable gene silencing