DNA Replication

Question 1

How many components do nucleotides have?

Answer 1

3 components

Question 2

What are the components of a DNA Nucleotide?

Answer 2

Phosphate group, sugar and Base

Question 3

How are DNA strands held together?

Answer 3

Anti-parallel strands are held together by hydrogen bonding

Question 4

What are the three general features of DNA replication|?

Answer 4

-Semi Conservative
-Bidirectional
- Occurs during S phase of the cell cycle

Question 5

Who suggested the self replication of DNA?

Answer 5

Watson and Crick

Question 6

How did Watson and Crick suggest self replication of DNA occurs?

Answer 6

One strand is taken from the parent strand, the other is a newly synthesised strand

Question 7

What did the Meselson and Stahl demonstrate?

Answer 7

That DNA replicated semi-conservatively

Question 8

What are the two steps to semi-conservative DNA replication?

Answer 8

-DNA unwound to separate template strands
-Addition new nucleotides linked by covalent bonding

Question 9

How is the sequence of DNA determined?

Answer 9

By complementary base pairing with bases on template strand

Question 10

What does it mean when DNA Replication is bidirectional?

Answer 10

replication proceeds in both directions

Question 11

During which part of the cell cycle does DNA Replication occur?

Answer 11

During the S phase.]

Question 12

Is eukaryotic DNA synthesis similar to prokaryotic DNA synthesis?

Answer 12

yes, however Eukaryotic DNA synthesis is more complex

Question 13

Why is DNA replication in eukaryotes more complex?

Answer 13

-Eukaryotic cells contain more DNA
-Chromosomes are Linear ( multiple replicons needed)
-DNA complexed with proteins (DNA packaging)

Question 14

what is the rate od DNA replication in eukaryotes?

Answer 14

2kb/min, one chromosomes every 35 days

Question 15

How tightly are nucleosomes packed?

Answer 15

They are tightened into 30nm fibres

Question 16

What does the packaging of eukaryotic DNA depend on?

Answer 16

Histones

Question 17

What are these histones?

Answer 17

positively charged proteins

Question 18

What is the relationship between DNA and histones?

Answer 18

DNA wraps around histones to form nucleosomes

Question 19

What does the phrase “beads on a string” refer to?

Answer 19

the beads are the tightly packed nucleosomes that are connected by linker DNA

Question 20

What else does DNA replication involve?

Answer 20

It involves enzymes and proteins

Question 21

How many proteins are involved in the replication of DNA?

Answer 21

7 proteins/enzymes

Question 22

Which enzyme is required for the unwinding of the DNA double helix

Answer 22

Topoisomerase

Question 23

Which enzyme is required for the separation of the DNA double helix into two strands

Answer 23

DNA helicase, by breaking the H bonds

Question 24

How does DNA Helicase break the H bonds?

Answer 24

DNA Helicase uses energy from ATP to break the H bonds

Question 25

Which enzyme catalyses the formation of phosphodiester bonds between nucleotides?

Answer 25

DNA POLYMERASE III

Question 26

What does DNA Polymerase III require to elongate the DNA chain?

Answer 26

-DNA Template strand to copy
-RNA Primer
4 dNTPs

Question 27

What is an RNA Primer?

Answer 27

A short piece of RNA

Question 28

In which direction does the chain elongate?

Answer 28

5’ to 3’

Question 29

What is the role of DNA Polymerase?

Answer 29

Catalyses the elongation of DNA chains

Question 30

What does the enzyme Primase do?

Answer 30

Synthesises an RNA Primer

Question 31

How are the two DNA strands joined together?

Answer 31

DNA Ligase

Question 32

What is the role of DNA Polymerase I?

Answer 32

The RNA primer is removed and replaced with DNA

Question 33

Which direction does DNA polymerase work in?

Answer 33

5’ to 3’

Question 34

What are the 2 strands called during replication?

Answer 34

the leading strand and discontinuous strand