Chromatin Remodeling

Question 1

Transposon/Transposase

Answer 1

mobile DNA elements, can move from one area in the genome to another
can bring other sequences with them
sometimes make copies of themselves when moving

Question 2

Micrococcal Nuclease Experiment

Answer 2

revealed the nucleosome as a repeating unit
microccocal nuclease cut the DNA backbone wherever it isn’t wrapped around the nucleosome
increments of 150-200 bp
because a limited amount was used, fragments found in various sizes

Question 3

Nucleosome

Answer 3

consists of 2 of each of the four core histones and 160bp of DNA wrapped around protein core twice

Question 4

Histone

Answer 4

proteins which are subunits of the nucleosome

have tails which can be modified to adjust how tightly the DNA gets wrapped around the histones

Question 5

Histone Tail Properties

Answer 5

can be modified to adjust how tightly wrapped DNA is
acetylation makes them less positive (more negative), so DNA is less attracted, becomes looser (phosphorylation does the same)
methylation makes it retain positive charge, so DNA is more attracted, tightly bound

Question 6

HAT Mechanism

Answer 6

decondenses chromatin by adding acetyl group, which reduce the charge on histone tails, reduce interaction, facilitate gene expression

Question 7

HDAC Mechanism

Answer 7

consdenses chromatin by removing acetyl group

increase charge on histone tails, increase interaction, lessen gene expression

Question 8

Heterochromatin

Answer 8

condensed DNA, inactive transcription

facilitated by chromodomain-containing proteins/HDACs (which binds to methylated lysines)

Question 9

Euchromatin

Answer 9

de-condensed DNA, active transcription

facilitated by bromodomain-containing proteins/HATs (which binds to acetylated lysines)

Question 10

Epigenetics

Answer 10

study of changes in gene expression that are NOT due to the DNA sequence
histone modifications, DNA methylation, RNA-mediated processes
the environment can affect a persons’ epigenome, causing changes in gene expression

Question 11

Heterochromatin/Euchromatin Status in Stem Cell vs Differentiated Cell

Answer 11

stem cells have lots of euchromatin, allow for potential activation of any gene during differentiation into somatic cells
somatic cells are confined to lineage specific gene expression pattern