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cell proliferation > chromatin > Flashcards

chromatin Flashcards

1
Q

what binds to the receptor to activate the signalling pathway to promote PKA

A

ligand

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2
Q

what one type of cell can give rise to at least 220 different cell types

A

stem cells

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3
Q

stem cells can give rise to how many different cell types

A

220

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4
Q

what are the two different structures of DNA

A

euchromatin and heterochromatin

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5
Q

what is the point in epigenetic regulation

A

to read genetic information in different manors enabling to generate the diff cells of our body

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6
Q

embryonic stem cells can form how many different layers

A

3

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7
Q

what are the 3 layers embryonic stem cells can form

A

mesoderm, ectoderm and endoderm

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8
Q

what are the 4 different cell types

A
  1. multipotent
  2. primitive progenitor
  3. lineage committed
  4. specialised blood
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9
Q

what do cells require before becoming specialised blood cells

A

further differentiation

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10
Q

what do injuries, tissue damage, tissue regeneration, sun exposure and ischemia require in order to regenerate

A

the cellular processes have to occur simultaneously and therefore required coordination

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11
Q

what enables stem cells and progenitor cells to re enter into proliferation and then differentiation

A

epigenetic regulations

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12
Q

what do epigenetic regulations enable stem and progenitor cells to do

A

to re enter into proliferation and then differentiate

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13
Q

what does epigenetic regulations enable stem cells and progenitor cells to differentiate into

A

regenerate tissue

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14
Q

what is it called when epigenetic enables to read the genetic information in different manners

A

cell plasticity or genome reprogramming

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15
Q

what is the human genome made out of

A

DNA

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16
Q

where is DNA stored

A

the nucleus of eukaryotic cells

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17
Q

how does a heterochromatin appear on a histogram compared to eurochromatin

A

darker

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18
Q

heterochromatin contains what kind of DNA?

A

compacted (inactive)

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19
Q

euchromatin contains what kind of DNA?

A

opened (active)

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20
Q

why is euchromatin open?

A

so it can be read

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21
Q

what structure do the euchromatin have

A

double stranded helical

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22
Q

DNA is complexed with histones to form what

A

nucleosomes

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23
Q

each nucleosome consists of how many histones?

A

8

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24
Q

how many times does the DNA wrap around the 8 histones

A

1.65 times

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25
Q

a chromatosome consists of what

A

a nucleosome plus the H1 histone

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26
Q

the nucleosome folds up to produce what?

A

a 30nm fiber

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27
Q

the 30nm fiber loops averaging what length?

A

300nm

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28
Q

the 300nm fibers are compressed and folded to produce a fiber at what width?

A

250nm wide fiber

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29
Q

tight coiling of the 250 nm fiber produces the chromatid of what

A

a chromosome

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30
Q

why cant heterochromatin genes be read

A

they are closed

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31
Q

what 8 histones form a nucleosome

A

2 H3, 2H4, 2 H2A and 2 H2B

32
Q

what level of DNA packing are nucleosomes

A

level 1

33
Q

what charge are AA’s within nucleosomes

A

positive

34
Q

where do the nucleosomes bind tightly to?

A

negatively charged DNA

35
Q

what is an example of 2nd level packing

A

solenoids/chromatin

36
Q

in a solenoid, H1 histones aggregate causing what?

A

6 nucleosomes to coil together

37
Q

solenoids stack on top of each other forming what?

A

a chromatin fiber

38
Q

where do chromatin fibres attach themselves to

A

wall of the nuclear membrane

39
Q

when chromatin fibers are attached to the wall of the nuclear membrane what do they form

A

loops by binding to nuclear membrane proteins

40
Q

in the nucleus of a non dividing cell, chromatin fibers form what

A

discrete chromosome territories

41
Q

chromosome territories are correlated with what

A

gene densities

42
Q

territories of chromosome domains that are relatively gene rich tend to be located towards what

A

the interior of the nucleus

43
Q

the interaction of DNA/nucleosomes is regulated by what

A

histone modifying enzymes that induce post translational modifications

44
Q

name examples of histone modifying enzymes

A
  1. histone acetyl transferase (HAT)
  2. acetyl coA
45
Q

how are the histone modifying enzymes produced (HAT and acetyl coA)

A

glycolysis on lysine

46
Q

what does lysine do in order to regulate the strength of the binding of histone to DNA and opens genes to be expressed

A

it is a positive AA which binds strongly to negative DNA

47
Q

what does lysine do once it has bound to the negatively charged DNA

A

regulates the bindings of histones to the DNA and opens chromatins/genes to be expressed

48
Q

how are the expression of histone modifying genes and the activity of the histone modifying enzymes regulated

A

by cellular receptors and by energy metabolism

49
Q

acetylation/deacetylation of the positively charged amino acid lysine regulates what

A

interaction of negatively charged phosphate on DNA

50
Q

what processes regulate the interaction with negatively charged phosphate on DNA

A

acetylation/deactylation

51
Q

HAT enzymes catalyse the transfer of what to what

A

acetyl group from acetyl co A

52
Q

how is acetyl co A produced

A

in the TCA cycle

53
Q

where are the epsilon amino groups of lysine’s located

A

in the N terminus of histones

54
Q

what does acetylation involve

A

abolishes the positive charge on lysine interacting with the negatively charged phosphate on the DNA backbone

55
Q

acetylation reduces what

A

the strength of the interaction histone/DNA

56
Q

interactions of DNA/nucleosomes is regulated by PTM but what is this induced by

A

cell signalling receptors and energy metabolism

57
Q

acteylation is an example of what process

A

PTM

58
Q

arginine an lysine can exist as what structures

A

mono, di, or tri-methylated

59
Q

what is methylation an example of

A

PTM

60
Q

what happens when a lysine is ubiquinated

A

increases the size of the lysine

61
Q

what is phosphorylation an example of

A

PTM

62
Q

phosphorylation can do what and why

A

repulses histones and DNA due to the several negative charges it places on the nucleotide (2)

63
Q

histones are modified where

A

on the C and N terminal domains

64
Q

what is the process that neutralises the positive charge of arginine

A

deamination or citrunillation

65
Q

what does deamination do to arginine

A

neutralises the positive charge, weakening the interaction with the negatively charged DNA, resulting in the opening of the chromatin

66
Q

methylation of lysine and arginine does what

A

regulates the hydrophobic interactions with histones

67
Q

histone modifying enzymes are expressed in what manner

A

tissue-dependant manner

68
Q

what do histone modifying enzymes do

A

open or close access to a gene

69
Q

for gene expression (transcription) to occur, the enzymes that synthesise RNA (RNA polymerase) must attach to what

A

a promotor region

70
Q

what enzymes synthesise RNA

A

RNA polymerase

71
Q

promotors contain specific DNA sequences called what

A

response elements

72
Q

how many different types of RNA polymerase are there

A

3

73
Q

the RNA polymerase auto assemble together to form what

A

RNA transcription machinery that binds and opens the double stranded DNA helix and then slide along the helix, this opens and closes the SNA whilst synthesising the new RNA molecule

74
Q

what are transcription factors

A

proteins that bind to specific DNA on a specific region to recruit the RNA polymerase to this specific location of the genome and initiate the transcription

75
Q

what 3 things can transcription factors bind to

A

enhancers, silencers and promoters

76
Q

what are enhancers

A

DNA sequences localised in non-coding regions (all but exons) to increase the chance that transcription of a particular gene will occur

77
Q

what are silencers

A

opposite of enhancers
made of DNA and bind to transcription factors like enhancers but they inhibit or abolish the gene transcription

cell proliferation (12 decks)

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