Chapter 12

Question 1

Replicon

Answer 1

Unit of replication. Each contains a single origin of replication

Question 2

Theta Replication

Answer 2

Double stranded DNA unwinds at origin producing single-stranded templates for synthesis of new DNA. Replication bubble forms with replication fork at each end. Forks move around the circle, producing two circular DNA molecules

Question 3

Rolling Circle Replication

Answer 3

.

Question 4

In eukaryotes, one replicon is approximately ____ in length

Answer 4

200000 to 300000 bp in length

Question 5

Initiation in bacterial replication

Answer 5

Initiator protein (DnaA) binds to origin and unwinds a small section of DNA

Question 6

What does helicase do

Answer 6

Binds to the lagging strand and breaks hydrogen bonds between bases as it moves from 5’ to 3’ direction

Question 7

Single Stranded Binding Proteins

Answer 7

Bind to single strands of DNA to prevent interference

Question 8

What does DNA gyrase (a topoisomerase) do?

Answer 8

Relieves torsion by making a doubt-stranded break

Question 9

Difference between Type I and Type II topoisomerase

Answer 9

Type I control super coiling by making single stranded breaks. Type II control supercoiling by making double stranded breaks

Question 10

DNA gyrase is a _____ _____

Answer 10

Type II topoisomerase

Question 11

What are RNA primers?

Answer 11

Group of RNA nucleotides with a 3’ OH

Question 12

Primase

Answer 12

Synthesizes RNA primers

Question 13

DNA polymerase III

Answer 13

Adds nucleotides in 5’ to 3’ direction

Removes nucleotides to correct errors in 3’ to 5’ directions

Question 14

DNA Polymerase I

Answer 14

5’ to 3’ exonuclease activity

Removes RNA nucleotides in primers and replaces them with DNA nucleotides

Question 15

DNA ligase

Answer 15

Seals breaks in strand. Joins Okazaki fragments

Question 16

How can termination occur?

Answer 16

Two forks meet, or termination sequence blocks replication (TER Site)

Question 17

Which polymerases exhibit 3’ to 5’ exonuclease activity?

Answer 17

DNA poly I, II, III

Question 18

Mismatch Repair

Answer 18

Errors corrected after replication is completed

Question 19

What are eukaryotic origins of replications called?

Answer 19

Autonomously replicating sequences

Question 20

How many DNA polymerases in eukaryotic replication?

Answer 20

14

Question 21

Function of alpha polymerases?

Answer 21

Initiation, primase activity

Question 22

Function of delta polymerase?

Answer 22

Synth lagging strand

Question 23

Function of epsilon polymerase?

Answer 23

Synth leading strand

Question 24

Translesion DNA polymerases

Answer 24

Can bypass errors and continue DNA replication. Low fidelity

Question 25

Telomerase

Answer 25

Extends DNA at the end of chromosome, filling in the gap

Question 26

Homologous recombination

Answer 26

Exchanges between homologous DNA molecules during crossing over

Question 27

Heteroduplex DNA

Answer 27

DNA with material from different chromosomes

Question 28

Holliday Junctions with single strand breaks result in

Answer 28

A crossover recombinant and a non crossover recombinant

Question 29

Function of RecBCD complex

Answer 29

Unwinds and cleaves double stranded DNA

Question 30

RecA

Answer 30

Allows invasion and displacement of DNA helix by single stranded DNA

Question 31

RuvA and RuvB

Answer 31

catalyze branch migration

Question 32

RuvC (resolvase)

Answer 32

Cleaves holliday junction