DNA Replication

Question 1

What bonds are broken during DNA replication?

Answer 1

H Bonds

Question 2

Where does DNA replication begin?

Answer 2

Origin of Replication (ORI)

Question 3

How many ORI’s are in a bacterial genome?

Answer 3

One

Question 4

TRUE OR FALSE:
Eukarotic genomes have many ORI’s

Answer 4

TRUE

Question 5

What 2 bases are most prevalent in the ORI?

Answer 5

A and T

Question 6

What is the difference between a bacterial genome and a eukaryotic genome?

Answer 6

• Bacterial genome is CIRCULAR
• Eukaryote genome is LINEAR

Question 7

DNA replication is:

A) Unidirectional

or

B) Bidirectional

Answer 7

B) Bidirectional

Question 8

Which end of a DNA strand are new nucleotides added to?

Answer 8

3’ end

Question 9

What does the new nucleotide add onto the 3’ end of the primer strand as?

Answer 9

Deoxyribonucleoside Triphosphate

Question 10

What does DNA polymerase require in order to work?

Answer 10

1. Template
2. Primer

Question 11

What can RNA polymerase do the DNA polymerase cannot?

Answer 11

Start an RNA chain from scratch

Question 12

What are the functions of DNA polymerase 1?

Answer 12

1. Polymerase (adding onto template strand)
2. 5’ exonuclease (correcting mistakes from 5’ to 3’)
3. 3’ exonuclease (correcting mistakes from 3’ to 5’)

Question 13

What are the functions of DNA Polymerase 3?

Answer 13

1. 3’ exonuclease
2. Polymerase

Question 14

What are the three stages of DNA replication?

Answer 14

1. Initiation
2. Elongation
3. Termination

Question 15

What happens at the Initiation stage of DNA replication?

Answer 15

• Starts at ORI
• Helicase unwinds helix in both directions
• Creates 2 replication forks
• Single stranded binding protein (SSB) prevents reassociation between unwound DNA strands

Question 16

What enzyme produces the primer for DNA polymerase?

Answer 16

Primase

Question 17

What is the enzyme that links DNA strands together?

Answer 17

DNA Ligase

Question 18

What happens at the Elongation stage of DNA replication?

Answer 18

Synthesis occurs in a 5’ to 3’ directions on BOTH STRANDS

Question 19

On which DNA strand is synthesis happening continuously?

Answer 19

The Leading Strand

Question 20

On which DNA strand is synthesis happening discontinuously?

Answer 20

The Lagging Strand

Question 21

Which is the major DNA replication enzyme?

Answer 21

DNA Polymerase III

Question 22

How does DNA synthesis happen on the LEADING STRAND?

Answer 22

1. RNA primer is synthesised
2. DNA Pol III adds DNA nucleotides to new strand
3. DNA Pol I removes RNA primer and fills in the gap (5’ to 3’)
4. DNA ligase links new DNA strands (phosphodiester bond)

Question 23

How does DNA synthesis happen on the LAGGING STRAND?

Answer 23

1. Made up of Okazaki Fragments each with its own primer
2. DNA Pol III extends the primer from the 3’ end
3. DNA Pol III stops at next RNA primer
4. DNA Pol I removes RNA primer and fills in gap
5. DNA ligase links the two new DNA strands (phosphodiester bond between 3’ OH and 5’ phosphate)