DNA replication

Question 1

DNA replication is

Answer 1

semi-conservative

Question 2

Semi-conservative

Answer 2

each daughter double helix contains one template strand and one newly synthesized strand

Question 3

protein involved in replicating double-stranded DNA

Answer 3

DNA polymerase

Question 4

Challenges in DNA replication

Answer 4

synthesis of two new daughter strands goes in opposite directions

how to unwind and separate the two parental strands

how to protect unwound portions from attack by nuclease

how to prevent errors in replication

Question 5

Negative supercoiling of chromosomal DNA makes it

Answer 5

underwound

Question 6

Underwinding DNA makes it

Answer 6

easier for the individual strands to be separated

Question 7

Two strands of DNA are separated by

Answer 7

hexameric helicase

Question 8

Volu=nerability of single-stranded DNA is defended by

Answer 8

Single stranded DNA binding domains (SSBs)

Question 9

SSB in eukaryotes

Answer 9

protein A

Question 10

DNA double helix unwinds at a specific point called

Answer 10

origin of replication

Question 11

At each origin of replication, there are

Answer 11

two replication forks

Question 12

According to the factory model of replication

Answer 12

protein machinery is stationary and DNA moves through it

Question 13

Leading strand

Answer 13

synthesized continuously from 5’ to 3’ end at the replication fork on the exposed 3’ to 5’ template strand

Question 14

lagging strand

Answer 14

synthesized semidiscontinously in small fragments or Okazaki fragments

Question 15

Fragments of the lagging strand are linked together by

Answer 15

enzyme- DNA ligase

Question 16

Prokaryotic DNA polymerases

Answer 16

DNA Pol I
DNA Pol III
DNA Pol II

Question 17

DNA Pol I does what

Answer 17

repair and patching of DNA

Question 18

DNA Pol III does what

Answer 18

main enzyme for synthesizing new DNA strand

Question 19

DNA Pol II does what

Answer 19

proofreading and repair enzyme

Question 20

DNA gyrase

Answer 20

relieves positive supercoils and relieves torsional strain

Question 21

Helicase

Answer 21

unwinds DNA helix and causes strand to separate

Question 22

SSB

Answer 22

stabilizes single stranded regions and prevents reannealing of DNA

Question 23

Primase

Answer 23

synthesizes the RNA primer

Question 24

DNA ligase

Answer 24

seals nicks in DNA

Question 25

DNA Pol I

Answer 25

removes the RNA primer

Question 26

DNA Pol III

Answer 26

responsible for new strand synthesis

Question 27

Pol

Answer 27

abbreviation for polymerase

Question 28

DNA gyrase is considered a

Answer 28

type II topoisomerase

Question 29

DNA gyrase creates a _____ in relaxed circular DNA relieving the supercoiling

Answer 29

nick

Question 30

Energy for DNA gyrase to do its job is provided by

Answer 30

hydrolysis of ATP to ADP and Pi

Question 31

what serves as a primer in DNA replication

Answer 31

RNA

Question 32

Primase uses the DNA template strand to

Answer 32

produce RNA primer sequence

Question 33

Newly formed DNA is linked to the

Answer 33

3'-OH of the RNA primer

Question 34

Okazaki fragments are formed on the lagging strand due to

Answer 34

the requirement for DNA synthesis in the 5' to 3' direction

Question 35

As the replication fork moves away, the RNA primer is removed by

Answer 35

DNA polymerase I

Question 36

____ makes the final covalent bond between Okazaki fragments

Answer 36

DNA ligase

Question 37

DNA synthesis is bi-

Answer 37

directional

Question 38

DNA replication occurs during the

Answer 38

S phase

Question 39

Errors in DNA replication cause

Answer 39

mutations

Question 40

Errors in replication spontaneously perhaps once in

Answer 40

10^6 base pairs

Question 41

Proofreading reduces errors to once in

Answer 41

10^10 base pairs

Question 42

Proofreading involves the removal of

Answer 42

nucleotides immediately after they are added to the growing DNA strand during replication

Question 43

3'-5' exonuclease activity of DNA Pol does what

Answer 43

removes incorrect nucleotides during DNA synthese

Question 44

Mutagens

Answer 44

agents that bring about a mutation

Question 45

Thymidine dimers

Answer 45

dimerization of adjacent thymidine caused by UV light

Question 46

Modified bases that cannot be directly repaired can be

Answer 46

removed and replaced