Semi-conservative Replication

Question 1

Why must dna be replicated before a nucleus divides?

Answer 1

To ensure that all the daughter cells have the genetic information to produce the enzymes and other proteins they need

Question 2

Why is dna replication very precise?

Answer 2

All the new cells are more or less genetically identical to the original one

Question 3

What 4 requirements are there for semi-conservative replication to take place?

Answer 3

• the four types of nucleotide each with their bases
• both strands of the dna molecule to act as a template for the attachment of nucleotides
• the enzyme DNA polymerase
• a source of chemical energy to drive the process

Question 4

What is the 1st step of semi-conservative replication?

Answer 4

• the enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.

Question 5

What is the 2nd step of semi-conservative replication? (Helix)

Answer 5

The double helix separates into its two strands and unwinds.

Question 6

What is the 3rd step of semi-conservative replication? (Template)

Answer 6

Each exposed polynucleotide strand acts as a template to which complimentary free nucleotides bind by specific base pairing.

Question 7

What is the 4th step to semi-conservative replication? (Enzyme)

Answer 7

Nucleotides are joined together by the enzyme DNA polymerase to form the “missing” polynucleotide strand on each of the two originals.

Question 8

Why is it called semi-conservative?

Answer 8

Each of the new DNA molecules contains one of the original DNA strands and so half the original DNA has been saved.

Question 9

What is the other replication model?

Answer 9

Conservative replication - one strand stays as it is and a whole new one is made out of free nucleotides