Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Control Of Gene Expression > Chromatin Structure > Flashcards

Chromatin Structure Flashcards

1
Q

Chromatin is dna wrapped around histones. What 2 types of histones are there

A

Core and linker histones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 types of core histones

A

H2A,b,3,4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 2 major parts of histones

A

N terminal tail

Globular domain (helixes and loops)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the interaction between core histones called

A

Handshake interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Core histones form nucleosomes with 2 dna wraps. How

A

H2a,b dimer x 2

Central H3,4 tetramer

= octamer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Is the octamer of core histones stable without dna

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do linker histones do Eg H1

A

Bind to dna between nucleosomes, forming a 30nm fibre instead of 10.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How was in vivo nucleosome positioning evidence that chromatin inhibits transcription

A

They found that during transcription nucleosomes were disrupted or lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What genetic study on cerevisiae showed nucleosomes inhibit transcription

A

Regulatable promoter gal4 was introduced before the H4 gene (for nucleosome tetramer)

When glucose was present this switched off gal4 and therefore stopped expression of H4

H4 not being expressed means less nucleosomes and this increased txn in the cerevisiae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What 3 ways is chromatin modified

A

Histones variants
Post translational modification
Atp dependant remodelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which of the 4 core histones doesn’t have a variant

A

H4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do histone variants change chromatin structure

A

Change structure of nucleosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 4 post translational mods of chromatin n terminal tails

A

Acetylation
Methylation
Ubiquitylation
Phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What AA are at n terminal tails

A

Lysine and arginine (basic) (+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which enzymes cause acetylation of lysine in n terminal tails and what do they use

A

HATs
Histone acetyl transferases

They use acetyl coa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to the positive charge of lysine when HATs acetylate it

A

Removed

17
Q

Which enzymes removed acetate from the n terminal lysines

A

HDACs

Histone deacetylases

18
Q

How do HDACs work

A

Hydrolysis (use h20 to remove acetate)

19
Q

Is the charge restored on lysine after histone deacetylation

A

Yes it goes back to positive

20
Q

What were Hats found to be homologous to which showed they increased transcription

A

GCN5 which is an activator in yeast

21
Q

What are the 2 HAT families

A

GNAT and MYST

22
Q

How do gnat and myst differ

A

They acetylate different histone n terminal tails

23
Q

What is post translational modifications of histones called

A

The histone code

24
Q

What do post translational modifications do which allows txn

A

Attract proteins which influence the txn machinery

25
Q

Why are Hats called co activators

A

Because they work with activators Eg gcn5 activator/HAT in yeast acts with tra1 and other activators to form saga complex

26
Q

How are hats brought to dna (2 ways)

A

Via activators Eg gcn5 in yeast attracted by tra1 and other activators to form saga

Or they can be part of the txn machinery

27
Q

What is the largest HAT which is associated already to txn machinery

A

Taf II 250

28
Q

What 2 ways does acetylation increase txn

A

1- removes positive charge from n terminal tail lysine : stops the interaction tight with negative dna in nucleosomes

2- attracts bromodomain proteins

29
Q

What do bromodomain proteins do

A

Up regulate transcription when recognise acetylated lysine

30
Q

How does bromodomain protein bdf1 work

A

Binds to acetylated H4

Attracts II d which starts pic

31
Q

As well as a HAT, what is taf 250

A

A bromodomain protein

32
Q

What gets methylated

A

Lysine and arginine

33
Q

Which enzymes methylate lysine on n terminal tails

A

HKMTs

Histone lysine methyl transferases

34
Q

What are the 3 types of methylated lysine via hkmt

A

Methyllysine

Dimethyllysine

Trimethyllysine

35
Q

Is methylation readily reversible like acetylation

A

No but de methylases exist

36
Q

Does methylation affect charge

A

No so don’t have a big impact on txn

37
Q

Which proteins are attracted by methylation which either activate or repress txn

A

Chromodomains, phd etc

38
Q

Methylation of what lysine residues on H3 are activating

A

4 and 36

39
Q

What lysine methylation on H3 is repressing

A

9 and 27

Control Of Gene Expression (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions