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Bio 331 Final Exam > Dna Organization And Cell Identity > Flashcards

Dna Organization And Cell Identity Flashcards

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Biology 101 flashcards
1
Q

What is differentiation

A

Cells specialize into different cell types

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2
Q

What is chromatin closure associated with

A

Differentiation

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3
Q

What does the histone code help with

A

Organizing chromatin and regulating gene expression

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4
Q

What happens to the chromatin on genes when cells are more differentiated

A

The chromatin for other cells types close and only the specific cells type genes and general cell function genes are on

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5
Q

Stem cells are

A

Least differentiated

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6
Q

What is a niche

A

A thing the allows the cells to keep its identity as a stem cell

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7
Q

Highly specialized cells can’t act as

A

Stem cells

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8
Q

Gene control cell. _____ and chromatin controls cell _____

A

Identity

Differentiation

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9
Q

What are bookmarks

A

A combination of of epigenetic marks and protien partners

that leave instructions on the genes to allow the cell to come back to its original state once changed

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10
Q

Can bookmarks be reprogrammed and how

A

Yes by the micro environment

The micro environment can control developmental decisions and cell identity

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11
Q

What is heterochromatin

Euchromatin

A

Tightly packed after mitosis inactive

Loosely packed dispersed active after mitosis

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12
Q

What do chromosomes consist of

A

Histones

Chromatin fibres

Nucleosomes

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13
Q

What are chromatin fibres

What are histones

What are nucleosome

A

Fibres. made of dna and is a accosiated protiens that wraps around the histones

Highly conserved protiens

The repeating subunit of dna and histones

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14
Q

What is histone H1

A

The linker between the dna and histones

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15
Q

A chromsome has a _______

A

Single dna molecule

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16
Q

What is the core complex

How many times does dna wrap around it

A

The histone octamer

DNA wraps around this 1.2x

17
Q

What is the core complex made of

A

2 of each

H2A

H2B
H3
H4

18
Q

What is the role of the histones

A

They have a amino terminal tail that sticks out past the dna

Modification of these tails can change the nucleosomes identity

Histones, regulatory protiens and enzymes can help alter dna transcription, compactions, replication, recombination, and repair

19
Q

What are epigenetic marks

A

Modifications to the histone tails

These can act as docking site to help non histone proteins park there

This can change the way that histones of nearby nucleosomes interact with the altered nucleosome

20
Q

What epigenetic histone modifications occur

A

Phosphorylation

Acetylation

Methylation

Ubiquitination

21
Q

What is the histone code hypothesis

A

The activity of a region of chromatin depends on the amount and specific type of chemical modification of the histone tails

22
Q

What is another thing that can silence chromatin

A

Small rnas

They recruit protiens that modify the histones

23
Q

What is dna methylation

Histone methylation

A

The 5th carbon of cytosine residues in dna get a methyl group added by dna methyl transferase

Histone methyl transferase add methyl’s (mono or di) to arg and lys residues of the histone protien

24
Q

What part of a histone get actyleated

How

A

Lysine residues of histones

HAT (adds)

HDAC (removes)

25
Q

What modification open chromatin

What closes

A

Added actetyl, HAT

remove acetly, add methyl (HDAC, HMT)

26
Q

Why is open chromatin more active

A

More room for transcriptional machinery

More thing and come in and bind

27
Q

What is an example of a protien bind to histones to change expression

A

Heterochromatin protien 1 (HP1)

It binds specifically to a methyl group to close the chromatin (basically activates the methyl group)

Binds to histone 3 on lysine 9 (H3K9)

28
Q

Is H3K9 is acetylated what does this mean

A

HP1 doesn’t bind since no methyl and chromatin is open

29
Q

What is a chromodomain

A

A domain on HP1 that binds to methylated amino acids (histone protiens)

30
Q

What is the function of H3K27ac

A

In interphase, pol 2 is on the chromatin

During mitosis it falls off

The marker H3K27ac acts as a marker To help pol 2 find where to go back to after mitosis is over

31
Q

What is a Barr body

A

Females have two X chromosomes but one is actually inactive and stays as a condense heteromatic clump

32
Q

How does a whole chromosome get silenced

A

Xist (x inactive specific transcript gene)

Binds specifically gene rich regions of the X chromosome

The expression of xist is enchanced and mutiple of them on the same chromsome trigger methylation

This inactivated the x chromosome

33
Q

What are progenitor cells

A

More specialized stem cells but not fully specialized cells

In middle of hierarchy

34
Q

Slide 25

A

Basically talking about how it cells are places into niches that aren’t their own they form cells of that niche

Bio 331 Final Exam (17 decks)

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