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Med 103 > DNA and genetics > Flashcards

DNA and genetics Flashcards

1
Q

what isomers are used to show that DNA is semiconservative (meselson stahl experiment)

A

Nitrogen 15 and 14

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2
Q

replicon

A

region of DNA, that replicates from a single origin of replication.

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3
Q

how many starting points does circular DNA have

A

one

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4
Q

what is the oric

A

origin of replication i.e. initiation point

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5
Q

oric is rich in……

A

adenine and thymine

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6
Q

how many sequences are there in the oric and how many base pairs

A

11 and 245. three repetitions of 13 base pairs and four repetitions of 9 base pairs

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7
Q

what protein complex helps recognize site of replication

A

origin recognition complex (ORC)

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8
Q

what initiation factors bind to the ORC

A

cdc6 and DUP/Cdt1

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9
Q

what do the initiation factors help load

A

MCM2–7 helicase complex

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10
Q

what do S-CDK and DDK do

A

recruitment of the helicase components Cdc45 and the GINS complex and other functions

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11
Q

what is activated at the start of S phase to begin replication

A

replicative helicase (composed of MCM2–7, Cdc45, and GINS)

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12
Q

what enzyme begins dissolution

A

helicase

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13
Q

what maintains the replication fork

A

single-stranded DNA binding proteins

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14
Q

name four DNA polymerase substrates and four RNA and polymerase substrates

A

dATP, dGTP, dCTP, dTTP and ATP, GTP,CTP,UTP

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15
Q

function of DNA polymerase I

A

replaces the primer with DNA

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16
Q

function of DNA polymerase II

A

repair

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17
Q

function of DNA polymerase III

A

main addition

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18
Q

what enzyme seals the gap during replication

A

ligase

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19
Q

what enzyme synthesizes primers

A

primase

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20
Q

what helps hold DNA pol in place during addition

A

sliding clamp

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21
Q

what enzyme helps relieve stress on DNA during unwinding

A

topiosomerase

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22
Q

how does topiosomerase work

A

catalyzes the removal of superhelical turns from covalently closed DNA by a transient breakage and rejoining of phosphodiester bonds.

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23
Q

what is the difference between TOP1 and TOP2

A

TOP1 cuts and repairs one strand while TOP2 cuts two

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24
Q

where do we fine replication fork traps

A

in bacteria for termination of protein synthesis

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25
Q

what repetitive sequence does telomerase add

A

TTAGGG

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26
Q

what is TERT and TERC

A

TERT gene provides instructions for making one component of an enzyme called telomerase
TERC is a component of telomerase

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27
Q

what is telomerase composed of

A

ribonucleoprotein

28
Q

what chemical group is obtained during telomerase adding

A

free 3’OH groups due to hydrogen bond formation between the Gs

29
Q

what cells have high telomerase activity

A

cancer and germ cells

30
Q

what is retrovir (Zidovudine) used for

A

controls HIV

31
Q

what term is used to describe cells are only
capable of a limited number of
population doublings in culture

A

hayflick limit

32
Q

out of different types of DNA which has a low mutation rate

A

single copy DNA

33
Q

what type of DNA has a high degree polymorphism

A

repetitive DNA

34
Q

what sequences have no genes

A

highly repetitive DNA

35
Q

where are highly repetitive sequences found

A

heterochromatin in telomeres or centromeres

36
Q

for highly repetitive sequences the repeating unit is not conserved. true or false

A

false. it is conserved

37
Q

which sequences are the shortest

a) moderately repetitive
b) highly repetitive
c) single copy

A

highly repetitive

38
Q

which sequences are involved

in organizing chromosome pairing during meiosis and recombination

A

highly repetitive

39
Q

what sequences are found in pericentromeric and telomeric heterochromatin regions

A

satellite DNA (highly repetitive)

40
Q

satellite sequences are

a) unique to individuals
b) unique to species
c) same among all species

A

unique to species

41
Q

what sequences are dispersed through euchromatin

A

moderately repetitive

42
Q

which sequence regulates gene expression

A

moderately repetitive

43
Q

what do interspersed DNA have ability to

A

jump from one place to another in the genome

44
Q

what advantage to plasmids provide

A

antibiotic resistance

45
Q

what are the types of interspersed DNA

A

RNA and DNA transposons

46
Q

what is the difference between RNA and DNA transposons

A

RNA transposons require conversion of DNA to RNA and back to DNA again while DNA trasnposons do not require an RNA intermediate

47
Q

what are the two groups of RNA transposons

A

LTR and non-LTR elements

48
Q

DNA transposons are retroelements while RNA transposons are not

A

false. other way around

49
Q

are endogenous retroviruses(ERVs) LTR or non LTR elements

A

LTR elements

50
Q

what are endogenous retroviruses

A

These are retroviruses integrated into the vertebrate chromosomes and inherited from generation to generation as part of the host genome

51
Q

what are the types of non LTR elements

A

LINEs and SINEs (short and long interspersed nuclear elements)

52
Q

which of these has reverse transcriptase, SINEs or LINEs

A

LINEs, SINEs borrow them from other retroelements

53
Q

Alu sequence is a example of what

A

SINEs

54
Q

what type of transposons are in Ac/Ds elements of maize

A

DNA transposons

55
Q

what are the types of tandem repeats

A

micro, mega and mini satellite DNA

56
Q

what is another name for microsatellites

A

short sequence repeats (ssr)

57
Q

majority of minisatellites are

1) A-T rich
2) G-C rich
3) A-U rich

A

G-C rich

58
Q

where are minisatellites clustered in chromosomes

A

subtelomeric regions

59
Q

variable number of tandem repeats

(VNTR) are also known as

A

minisatellites

60
Q

telomeric repeats are

1) A-U rich
2) G-C rich
3) G-T rich
4) G-G rich

A

G-T rich

61
Q

where are subtelomeric repeats located

A

adjacent to the telomere

62
Q

where are hypervariable repeats located

A

within nuclear DNA or the D-loop of mitochondrial DNA

63
Q

hypervariable repeats are moderately polymorphic, true or false

A

false. they are highly so

64
Q

what is an examples of mega-satellites composed of coding repeats

A

RNA genes, and the deubiquitinating enzyme gene USP17

65
Q

what is another name for microsatellites

A

simple sequence repeats (SSRs)

Med 103 (13 decks)

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