W3 L2 Chromatin and Histone regulation of genes W

Question 1

Accessing DNA from histone

Answer 1

! Nucleosomes need to be displaced for DNA replication, repair, recombination and transcription.
-Enzyme is used for sliding using ATP as energy sources

Question 2

what is Chromatin remodeling and histone modification

Answer 2

! Nucleosomes can be moved along DNA
! Histones can be exchanged or kick out nucleosomes

Question 3

Different type of chromosome remodeller

Answer 3

Question 4

Returning nucleosome to it;s original structure

Answer 4

-need histone chaperone- FACT
-bind to the nucleosome, loosen it.
-After the RNA pol move through, they reasemble it

Question 5

Histone modification

Answer 5

-modifying histone tail which vary in length
-histone fold domain is reserved
-after folding, the histone tail will hang out from the structure, can be easily Cleve by protease treatment

Question 6

Different state of histone tail

Answer 6

-Phosphorylation
-Methylation
-acetylation
Modification can show the state of the gene or the cell, some are overlapping

Question 7

Histone modification example in Drosophila

Answer 7

-In drosophila, sex can be determine by upregulation of expression for genes on the X chromosome
-In males, expression of genes on the X is doubled
! Mediated by msl-2 (male-specific lethal 2)
! In females, Sxl blocks translation of msl-2 mRNA
MLS2 only activate in male, recruited to X chromosome, lead to histone H4 K16 acetylation.
roX1 and roX2 expressed in male due to MSL2 complex binding

Question 8

Monoallelic expression

Answer 8

-even though organism have two copy of the gene, some gene are expressed monoallelicly (by one allele)
-many method of selection, maternal, paternal or random

Question 9

Histone modification lead to heterochromatin creation

Answer 9

! H3K9me promotes binding of Heterochromatin Protein (HP1)
! Leads to establishment of heterochromatin
! H2S10P reverses binding by HP1

Question 10

Epigenetic meaning

Answer 10

• traits that is a stably heritable phenotype due to changes in chromosome without altering the DNA sequences

Question 11

Epigenetic pathway

Answer 11

! Transmitted from parent to daughter cells
! Epigenetic phenotypes stable through mitosis

Question 12

Somatic vs germ line Epigenetic inheritance

Answer 12

Meiosis tend to lose chromatin state with the exception of imprinting

Question 13

Imprinting in depth

Answer 13

-imprinting is Epigenetic inheritance between generation, as the chromatin is preservered in the germ cell

Question 14

How Epigenetic inheritance work

Answer 14

-via stable regulatory loop
One gene is turned off but but it’s product can bin to the promoter region and turn it on
-if there are many gene product, the daughter cell will have it’s gene turned on

Question 15

Candida albicans Example

Answer 15

-two morphological state white and opaque
-In white cell EFG1 prevent WOR2 which change the gene to opaque gene
-WOR1 turn on WOR2, also CZF1 . CZF1 prevent EFG1, so does WOR1. No white cell

Question 16

Inheritance of epigenetic between mother and daughter cell

Answer 16

• a newly created DNA inherit the histone modification (chromatin pattern)of the mother cell
  -inherit DNA methylation pattern
  -inherit stable protein conformation

Question 17

Random X chromosome inactivation in mammals

Answer 17

-a paternal X or maternal X is turned off, this is inherited in the gene lineage