DNA replication, repair, and recombination

Question 1

mutation rate definition

Answer 1

the rate at which changes occur in DNA sequences

Question 2

bacteria mutation rate

Answer 2

3 per 10^10 nucleotides copied

Question 3

human mutation rate

Answer 3

1 per 10^10 nucleotides copied per cell division

Question 4

in germ line:

Answer 4

one change per 10^8 per human generation

100 generations occur in the germ line

Question 5

what is necessary for life as we know?

Answer 5

low mutation rates

Question 6

human genome is ____ nucleotides

Answer 6

3.1 x 10^9

Question 7

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

Answer 7

unchanged or changed minimally each time a typical human cells

Question 8

the accuracy of replication

Allows:

Answer 8

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

Question 9

the accuracy of replication:

reduces:

Answer 9

the changes in somatic cells that lead to cancer

Question 10

__________ underlies DNA replication and DNA repair

Answer 10

base-pairing

Question 11

what is DNA polymerase?

Answer 11

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

Question 12

what are the substrates of DNA polymerase?

Answer 12

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

Question 13

DNA polymerases synthesizes in the _____________ direction

Answer 13

5’ to 3’ direction

Question 14

DNA polymerase can synthesize DNA at rates as high as…

Answer 14

1000 nucleotides per second

Question 15

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

Answer 15

ATP hydrolysis

Question 16

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

Answer 16

pyrophosphate (PP)

Question 17

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

Answer 17

drive the overall reaction in the direction of polynucleotide synthesis

Question 18

what are the products of ATP hydrolysis?

Answer 18

2 ADP + 2 P

Question 19

the DNA replication fork is….shaped

Answer 19

asymmetrically

Question 20

semiconservative replication:

Answer 20

one strand is conserved in helix

Question 21

replication fork definition

Answer 21

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

Question 22

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

Answer 22

leading stand & lagging strand

Question 23

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

Answer 23

leading strand

Question 24

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

Answer 24

lagging strand

Question 25

lagging strand is composed of...

Answer 25

Okazaki fragments

Question 26

why are lagging strands made of discontinuous lengths?

Answer 26

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.

Question 27

Okazaki fragments are _________ nucleotides long in eukaryotes

Answer 27

100-200

Question 28

high fidelity of DNA replication depends on

Answer 28

-initial base pairing -proofreading mechanisms

Question 29

proofreading mechanisms: just before a new nucleotide is covalently linked to the growing chain, ....

Answer 29

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

Question 30

incorrectly paired nucleotides are more likely to...

Answer 30

diffuse away before the polymerase can covalently link them

Question 31

proofreading mechanisms: exonucleolytic proofreading

Answer 31

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

Question 32

DNA polymerase requires a previously formed...

Answer 32

base paired 3' OH end of a primer strand

Question 33

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

Answer 33

polymerase has difficulty extending such a strand

Question 34

another proof reading mechanism is

Answer 34

strand-directed mismatch pair

Question 35

during DNA synthesis, _________ proofreads its own work

Answer 35

DNA polymerase

Question 36

replication steps

Answer 36

5' to 3' polymerization 3' to 5' exonucleolytic proofreading strand directed mismatch repair combined