New: DNA Replication

Question 1

which phase of the cell cycle does DNA replicate?

Answer 1

S phase

Question 2

Semiconservative replication was first suggested by who

Answer 2

watson and crick

Question 3

3 models of replication

Answer 3

conservative; dispersive; semiconservative

Question 4

conservative model of replication

Answer 4

old duplex is conserved and new duplex composed of to completely new strands

Question 5

dispersive model of replication

Answer 5

sections of the old duplex dispersed somewhat randomly to the two daughter strands

Question 6

semiconservative model of replication

Answer 6

two daughter duplexed with one each of the old and new strands

Question 7

the ____ of DNA contain ___

Answer 7

bases; nitrogen

Question 8

Matthew Meselson and Franklin Stahl used what in their experiment

Answer 8

E. coli; naturally occurring N14 and heavy N15 isotopes of nitrogen; ultracentrifuge; pulse-chase experiments

Question 9

isopycnic

Answer 9

equal density

Question 10

Meselson-Stahl explanation

Answer 10

first generation results eliminated conservative model (after 1 generation DNA contained 50/50 N15 and N14)

second generation results eliminated dispersive model

Question 11

DNA replication occurs in a

Answer 11

semi-conservative manner

Question 12

Each strand of DNA acts as a

Answer 12

template for synthesis of a new strand

Question 13

Daughter DNA contains one parental and one

Answer 13

newly synthesized strand

Question 14

three stages of DNA replication

Answer 14

initiation; elongation; termination

Question 15

much of what we know about DNA replication is because of

Answer 15

E. coli

Question 16

DNA replication must be ____ and _____

Answer 16

rapid and accurate - mistakes can be lethal

Question 17

___ and ____ play a role in keeping DNA replication accurate

Answer 17

repair and recombination

Question 18

DNA is replicated by

Answer 18

polymerases

Question 19

which polymerases play a key role in DNA replication

Answer 19

1 and 3

Question 20

DNA polymerase catalyzes

Answer 20

phosphodiester bond formation

primer with free 3’ - OH –dNTP–> template strand (utilizes 1 dNTP at a time) –> replicated strand + PPi

Question 21

The reaction catalyzed by DNA polymerase s

Answer 21

(DNA)n + dNTP (DNA)n+1 +PPi

Question 22

5 important characteristics of DNA synthesis

Answer 22

1. Deoxynucleoside triphosphates and Mg2+ are required (dATP, dGTP, dCTP, dTTP)
2. A template strand is used to direct DNA synthesis
3. A primer from which the new strand grows must be present
4. Utilizes ONE NUCLEOTIDE (dNTP) at a time (but very fast)
5. many DNA polymerases have nuclease activity that allows for the removal of mismatched bases

Question 23

chain elongation is what type of reaction

Answer 23

nucleotidyl-group-transfer reaction

Question 24

nucleotides are added one at a time to the ____ end

Answer 24

3’

Question 25

chain extension is always ___ to ___ prime end

Answer 25

5' to 3'

Question 26

what step of DNA chain elongation makes the reaction irreversible?

Answer 26

pyrophosphatase

Question 27

DNA polymerase 1 possesses 3' to 5' exonuclease activity aka

Answer 27

proofreading

Question 28

polymerase 1 can catalyze both chain

Answer 28

elongation and degradation

Question 29

polymerase 1 recognizes distortion in the DNA caused by incorrectly

Answer 29

paired bases

Question 30

exonuclease activity removes

Answer 30

mispaired nucleotide before continuing

Question 31

pairs of amino acids

Answer 31

C-G (triple bond) | T=A

Question 32

proofreading by the 3' --> 5' exonuclease

Answer 32

finds removes and repairs mistakes

Question 33

E. coli chromosome is

Answer 33

circular, double stranded DNA

Question 34

replication of ecoli begins at the

Answer 34

oriC = origin of replication

Question 35

DNA replication of ecoli proceeds

Answer 35

bidirectionally until the two replication complexes meet at the termination site (ter)

Question 36

purpose of DnaA

Answer 36

binds to the oriC region --> keys DNA polymerase | and recruits DnaB (helicase activity)

Question 37

replisome

Answer 37

protein machinery for replication (one replisome at each of 2 replication forks)

Question 38

in ecoli, new strands of DNA are synthesized at the

Answer 38

two replication forks where replisomes are located

Question 39

unwinds DNA

Answer 39

helicase

Question 40

generates RNA primer

Answer 40

primase

Question 41

single stranded binding protein (SSB)

Answer 41

binds to ssDNA and prevents re-annealing of the helix; they exist as tetramers; each tetramer binds A-T rich sites; binding is cooperative; ssDNA with SSB is inflexible

Question 42

the resulting complex of DNA and proteins is called the

Answer 42

prepriming complex

Question 43

DnaB is

Answer 43

``` a helicase (molecular zipper); moves with directionality and processivity (holds on and doesn't let go) utilizes ATP to separate annealed DNA strands ```

Question 44

What can happen from a defect in the helicase

Answer 44

Werner's syndrome --> premature aging

Question 45

Can DNA polymerase initiate new strands

Answer 45

NO unable to covalently link 2 individual nucleotides together; they ARE able to covalently link a nucleotide to a PRIMER

Question 46

RNA primer is synthesized by

Answer 46

primase

Question 47

primase enables

Answer 47

DNA synthesis to begin; synthesizes short RNA complementary to a DNA strand that then serves as a primer for DNA synthesis DNA Template ---Primase---> RNA primer w/ template ---DNA polymerase---> Newly synthesized DNA strand w. template strand

Question 48

what is the site of replication called

Answer 48

replication fork

Question 49

replication fork moves in

Answer 49

1 direction, so both strands are copied simultaneously; however DNA polymerases synthesize DNA only in the 5' --> 3' direction

Question 50

Okazaki fragments

Answer 50

copy the lagging strand, which is lead by RNA primer