DNA organization Flashcards

1
Q

These sequences are repeated many times within eukaryotic chromosomes

A

Repetitive DNA sequences

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2
Q

which type of DNA consists of short repeated sequences, rarely transcribed into RNA and highly repetitive

A

Satellite DNA

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3
Q

which type of DNA appears one after the other in clusters at particular regions on the chromosome

A

Tandem repeats

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4
Q

this repeating DNA sequences 15 to 100 bp long and are found within and between genes

A

Variable number tandem repeats (VNTRS)

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5
Q

these sequences are dispersed throughout genome consistsing of di,tri, tetra nucleotides

A

Short tandem repeats (STRs)

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6
Q

what type of repeats are dispersed throughout genome and constitute 1/3 of human genome

A

Interspersed repeats

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7
Q

what type of interspersed element has 300bp sequence present more than a million times

A

Alu, SINES (short interspersed elements)

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8
Q

what repeats has several thousand base pairs with remnant of transposable elements

A

Line 1 Long interspersed elements (LINES)

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9
Q

if DNA is over or under twisted, what happens

A

it will supercoil if the ends can’t rotate

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10
Q

when DNA helix is underwound by 2 turns or some coils were removed

A

it is underwound circular DNA

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11
Q

when ends 1 seal to end 20, this is called

A

relaxed circular DNA

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12
Q

when DNA helix has a conformational change and 2 supercoils form

A

this is supercoiled DNA

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13
Q

what enzyme can sever DNA and rotate ends before rejoining

A

Topoisomerase

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14
Q

Agarose gel electrophoresis seperate DNA based on

A

size, charge and shape

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15
Q

which fragment move faster on gel smaller /larger

A

smaller

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16
Q

DNA fragment move towards with pole

A

positive electrode

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17
Q

whcih runs faster on a gel supercoiled DNA/ linear DNA/ circular DNA

A

supercoiled DNA

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18
Q

which chromosomes has circular, double stranded DNA compacted into nucleoid

A

Bacterial chromosomes

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19
Q

Is nucleoid nuclei based or not

A

it is not

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20
Q

BACTERIAL chromosomes DNA are associated with what protein

A

HU nad H-NS (histone like-nucleoid structuring protein)

21
Q

At interphase, eukaryotic chromosomes uncoil and decodnense into a form ccalled

A

Chromatin dispersed throughout the nucleus

22
Q

Chromatin appears as

A

beads on a string (nucleosomes)

23
Q

which chromatin is transcriptionally active and uncoiled

A

Euchromatin

24
Q

How do chromatin become visisble chromosomes

A

during cell division, chromatin coils and condenses back into visible chromosomes

25
Q

what are the core histones

A

H2A,H2B,H3,H4

26
Q

Which basic protein binds very well to negatively charged DNA

A

Arginine Lysine (positiveky charged)

27
Q

what digests of chromatin releases and further digest yielding fragment

A

micrococcal nuclease

28
Q

what protects DNA from nuclease enzyme

A

DNA wrapped in histones

29
Q

describe process of how nuclease attacks DNA

A
  1. A small amount of nuclease cleave the “strings fo the bead”
  2. release individual beads attached to about 200 bp of DNA
  3. more nuclease destroys all of the unprotected DNA between beads
  4. leaving a core of protein attached to 145-147 bp of DNA
30
Q

Nucleosomes organize into

A

filament

31
Q

which chromatin is mostly inactive and appears stained during interphase

A

Heterochromatin

32
Q

which chromatin appears unstained in interphase

A

Euchromatin

33
Q

which is less condensed between euchromatin/ herterochroimatin

A

euchromatin

34
Q

To allow replication and gene expression, chromatin must do what

A
  1. relax compact structure
  2. expose regions of DNA to regulatory protein
  3. have a reversal mechanism for inactivity
35
Q

what chromosomes is created by repeated round of DNA replication with no cell division

A

Polytene chromosome

36
Q

this region is where chromosome is made less compact

A

chromosomal puff

37
Q

chromosomal puff region is more sensitive to DNase I cleavege true/false

A

true

38
Q

characteristics of expanded regions

A

active transcirption

39
Q

sensitivity of DNA to digestion by DNase I is correlated with

A

gene expression

40
Q

what enzyme is involved in histone acetylation

A

histone acetyltransferase

41
Q

addition of what group to the positively charged amino group on side chain (lysine) changes net charge of protein

A

acetyl group

42
Q

histone acetylation promotes

A

gene activity

43
Q

what enzyme is involved in methylation

A

methyltransferase

44
Q

adding of methyl group to arginine and lysine leads to

A

repression or activation

45
Q

What enzyme is involved in phosphorylation

A

kinase

46
Q

phosphate group adds to hydorxyl group of which amino acids

A

serine and histidine

47
Q

what is the DNA sequence 5’-CG-3’

A

CpG

48
Q

methylation of which group by DNA methyltransferase repress gene activity

A

cytosine

49
Q

epigenetics changes are heritable true/false

A

true