DNA Replication

Question 1

What is DNA replication?

Answer 1

The process by which a DNA molecule reproduces itself to form an exact copy.

Question 2

Why is DNA replication carried out

Answer 2

This process ensures that new cells have a complete set of genetic information (same number of chromosomes and genes) as the original cell

Question 3

What are the 3 hypothesised replication methods and which is correct?

Answer 3

Conservative

Dispersive

Semi - conservative = CORRECT

Question 4

Requirements for DNA replication

Answer 4

DNA (to act as the template)

Primers (to start replication)

A supply of the four types of DNA nucleotides

DNA polymerase and ligase enzymes

A supply of ATP

Question 5

Function of DNA helicase

Answer 5

Unzips parent strand - separates strands by breaking hydrogen bonds between bases

Question 6

Function of DNA polymerase

Answer 6

Joins complementary nucleotides to 3’ end of strand by sugar-phosphate bonding

Question 7

Function of DNA ligase

Answer 7

Joins DNA fragments in lagging strand

Question 8

Function of primers

Answer 8

Allow for a starting point for DNA replication

Different primers are needed to target different stands (leading and lagging)

Question 9

What happens when a happens when a long chromosome is being copied?

Answer 9

Many replication strands open simultaneously to speed up the replication process

Question 10

How is the leading strand formed during DNA replication?

Answer 10

DNA helicase separates parent stand into leading and lagging stands by breaking weak hydrogen bonds between bases

A primer attaches to the 3’ end and nucleotides are lined up beside their complementary base pair in the stand

The nucleotides are joined together by DNA polymerase at the 3’ end

The direction of replication is 3’ to 5’

The primer is replaced with DNA

This process happens simultaneously to the replication of the lagging strand

Question 11

How is the lagging strand formed during DNA replication?

Answer 11

DNA helicase separates parent stand into leading and lagging stands by breaking weak hydrogen bonds between bases

Primers attach throughout the strand as a starting point for nucleotides to be lined up beside their complementary base pair in the stand

These nucleotides are joined by DNA polymerase in 3’ to 5’ direction

The fragments of replicated DNA have their primers replaced with DNA and are joined by DNA ligase

This process happens simultaneously to the replication of the leading strand