Ch 8 Genomes

Question 1

What is positive supercoiling?

Answer 1

DNA is overwound

Question 2

What is negative supercoiling?

Answer 2

DNA is underwound

Question 3

Who possesses negative supercoiling?

Answer 3

Eukaryotes, bacteria, and most archaea

Question 4

Who possesses positive supercoiling?

Answer 4

Archaea living in acid at high temperatures

Question 5

Which enzyme changes DNA supercoiling

Answer 5

topoisomerase

Question 6

What does Type I topoisomerase do?

Answer 6

Cleaves on DNA strand and use single proteins (less negative supercoils)

Question 7

What does Type II topoisomerase do?

Answer 7

Cleaves both strands of DNA, has multiple units

Question 8

_________is an example of Type__ topoisomerase

Answer 8

DNA gyrase, II

Question 9

What antibiotic targets DNA gyrase?

Answer 9

Quinolone

Question 10

What is semiconservative DNA replication?

Answer 10

Each daughter cell receives one parental and one newly synthesized strand

Question 11

Where does bacterial replication begin?

Answer 11

Origin (oriC)

Question 12

Where does bacterial replication end?

Answer 12

Termination (ter) sites

Question 13

What is DnaA?

Answer 13

The initiator protein

Question 14

What is DnaB?

Answer 14

Helicase

Question 15

What is DNA primase?

Answer 15

Synthesis of RNA primer

Question 16

What is DNA Pol III?

Answer 16

A major replication enzyme

Question 17

What is DNA Pol I?

Answer 17

Replaces RNA primer with DNA

Question 18

What is DNA gyrase?

Answer 18

Relieves DNA supercoiling

Question 19

What does the sliding clamp do?

Answer 19

Tethers DNA pol. to DNA so it doesn’t fall off

Question 20

What is the leading strand?

Answer 20

Replicated continuously in the 5’-3’ direction

Question 21

What is the lagging strand?

Answer 21

Replicated discontinuously in stages

Question 22

What are Okazaki fragments?

Answer 22

Synthesized DNA fragments linked together by DNA ligase to form the lagging strand

Question 23

What does the replisome do?

Answer 23

Makes sure that the leading and lagging strand go in the 5’-3’ direction

Question 24

How to get rid of RNA primers?

Answer 24

RNase H

Question 25

What does helicase do?

Answer 25

Temporarily separates double helix strands so DNA/RNA synthesis can occur

Question 26

What do tus proteins do?

Answer 26

Act as a counter-helicase to stop DNA synthesis

Question 27

What are ringed catenanes?

Answer 27

They form at the end of replication to be separated by topoisomerase IV

Question 28

What are plasmids?

Answer 28

DNA molcs. that replicate independently

Question 29

True or False: Plasmids can be resistant to antibiotics

Answer 29

True

Question 30

True or False: Plasmids cannot be transferred amongst cells

Answer 30

False

Question 31

What direction do plasmids replicate?

Answer 31

Bidirectionally and rolling-circle

Question 32

True or False: Archaea replication resembles that of eukaryotic replication

Answer 32

True