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cell bio Q2 > DNA replication, repair, and recombination > Flashcards

DNA replication, repair, and recombination Flashcards

slides 1-7

1
Q

mutation rate definition

A

the rate at which changes occur in DNA sequences

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2
Q

bacteria mutation rate

A

3 per 10^10 nucleotides copied

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3
Q

human mutation rate

A

1 per 10^10 nucleotides copied per cell division

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4
Q

in germ line:

A

one change per 10^8 per human generation

100 generations occur in the germ line

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5
Q

what is necessary for life as we know?

A

low mutation rates

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6
Q

human genome is ____ nucleotides

A

3.1 x 10^9

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7
Q

due to the high accuracy of replication, the sequence of the human genome is….

A

unchanged or changed minimally each time a typical human cells

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8
Q

the accuracy of replication

Allows:

A

one generation to pass accurate info the the next through germ cells (gametes)

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9
Q

the accuracy of replication:

reduces:

A

the changes in somatic cells that lead to cancer

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10
Q

__________ underlies DNA replication and DNA repair

A

base-pairing

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11
Q

what is DNA polymerase?

A

an enzyme that synthesizes DNA by joining nucleotides together using a DNA template as a guide

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12
Q

what are the substrates of DNA polymerase?

A

the four nucleotides: A, G, C, and T

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13
Q

DNA polymerases synthesizes in the _____________ direction

A

5’ to 3’ direction

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14
Q

DNA polymerase can synthesize DNA at rates as high as…

A

1000 nucleotides per second

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15
Q

synthesis of a polynucleotide (RNA or DNA) is a multistep process driven by…

A

ATP hydrolysis

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16
Q

adding a nucleotide to the growing chain results in the release of ______

A

pyrophosphate (PP)

17
Q

hydrolysis of the PP to inorganic phosphate is highly favorable and helps to…

A

drive the overall reaction in the direction of polynucleotide synthesis

18
Q

what are the products of ATP hydrolysis?

A

2 ADP + 2 P

19
Q

the DNA replication fork is….shaped

A

asymmetrically

20
Q

semiconservative replication:

A

one strand is conserved in helix

21
Q

replication fork definition

A

Y-shaped region of a replicating DNA molecule

the point at which the 2 strands of parent DNA helix are being separated and the daughter strands are being formed

22
Q

the two newly synthesized strands of DNA found at the replication fork are called

A

leading stand & lagging strand

23
Q

the ___ strand is made by continuous synthesis in the 5’ to 3’ direction

A

leading strand

24
Q

the ____ strand is made in discontinuous lengths that are later joined covalently

A

lagging strand

25
Q

lagging strand is composed of…

A

Okazaki fragments

26
Q

why are lagging strands made of discontinuous lengths?

A

the lagging strand is synthesized in the opposite direction of the replication fork, requiring the synthesis of short fragments that are later joined to form a complete strand.

27
Q

Okazaki fragments are _________ nucleotides long in eukaryotes

A

100-200

28
Q

high fidelity of DNA replication depends on

A

-initial base pairing
-proofreading mechanisms

29
Q

proofreading mechanisms:

just before a new nucleotide is covalently linked to the growing chain, ….

A

DNA polymerase must undergo a conformational change to tighten its grip around the active site

30
Q

incorrectly paired nucleotides are more likely to…

A

diffuse away before the polymerase can covalently link them

31
Q

proofreading mechanisms:

exonucleolytic proofreading

A

3’ to 5’ proofreading exonuclease activity of the DNA polymerase removes unpaired or misfired residues to regenerate a correctly base paired 3’ OH terminus that can prime DNA synthesis

32
Q

DNA polymerase requires a previously formed…

A

base paired 3’ OH end of a primer strand

33
Q

molecules with a improperly base paired nucleotide at the 3’ OH end of the primer strand are not effective as templates because…

A

polymerase has difficulty extending such a strand

34
Q

another proof reading mechanism is

A

strand-directed mismatch pair

35
Q

during DNA synthesis, _________ proofreads its own work

A

DNA polymerase

36
Q

replication steps

A

5’ to 3’ polymerization

3’ to 5’ exonucleolytic proofreading

strand directed mismatch repair

combined

37
Q
A

cell bio Q2 (6 decks)

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