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Cell proliferation > Chromatin > Flashcards

Chromatin Flashcards

1
Q

what binds to the receptor to activate the signaling 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 types of cells

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 of epigenetic regulation

A

to read genetic information in different manors enabling to generate the different 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 three layers embryonic stem cells can form

A

mesoderm
endoderm
ectoderm

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8
Q

what are the 4 different cell types

A

multipotent
primitive progenitor
lineage committed
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

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

A

the cellular processes have to occur simultaneously and therefore require coordination

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11
Q

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

A

epigenetic regulations

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12
Q

what to 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

epigenetic enables to read the genetic information in different manners, what is this called

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 euchromatin

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 30 nm fiber

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27
Q

the 30 nm fiber forms 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

250 nm 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 can’t heterochromatin genes be read

A

they are closed

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31
Q

what 8 histones form a nucleosome

A

2 H3
2 H4
2 H2A
2 H2B

32
Q

nucleosomes are what level of DNA packing

A

1st level

33
Q

what charge of amino acids are in a nucleosome

A

positive

34
Q

where do the nucleosomes bind tightly to and what charge

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 fibers 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 chromosone 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

towards 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

histone acetyl transferase (HAT)
Acetyl co A

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

its a positive amino acids which binds strongly to negatively charged 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/deacetylation

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 lysines 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/nucleosome is regulated by PTM but what is this induced by

A

cell sigaling receptors and energy metabolism

57
Q

acetylation is an example of what process

A

PTM

58
Q

arginine and 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 ubiquitinated

A

increases the size of lysine

61
Q

what is phosphorylation an example of

A

PTM

62
Q

phosphorylation can do what and why

A

repulses histone and DNA due due to the the several negative charges

63
Q

histones are modified where

A

on the N terminus and C terminal domains

64
Q

what is the process that neutralises the positive charge of arginine

A

deimination or citrunillation

65
Q

what does demination (citrunillation) do to arginine

A

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

66
Q

methylation of lysine and arginine do what

A

regulates the hydrophobic interactions with histones
weakens the interactions between histones and DNA

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
regulating gene expression

69
Q

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

A

a promotor region

70
Q

what enzymes synthesises 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 DNA while synthesising the RNA molecule

74
Q

what are transcription factors

A

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

75
Q

transcription factors can bind to what 3 things

A

promotos, enhancers, or silencers

76
Q

what are enhancers

A

DNA sequences localalised in non coding regions (everything that is not an exon) 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 (3 decks)

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