Replication of DNA

Question 1

What happens prior to cell division?

Answer 1

Prior to cell division, DNA is replicated by a DNA polymerase. DNA polymerase needs primers to start replication. A primer is a short strand of nucleotides which bind to the 3’ end of the DNA template allowing polymerase to add DNA nucleotides.

Question 2

Stages of DNA replication.

Answer 2

DNA polymerase adds DNA nucleotides, using complementary base pairing, to the deoxyribose (3’) end of the new DNA strand which is forming.

DNA is unwound and the hydrogen bonds between bases are broken to form two template strands. DNA polymerase can only add DNA nucleotides in one direction resulting in the leading strand being replicated continuously and the lagging strand replicated in fragments.

Fragments of DNA are then joined together by an enzyme called ligase.

Question 3

Name the enzyme that joins fragments of DNA together

Answer 3

Ligase joins fragments of DNA together.

Question 4

State the function of a primer

Answer 4

Primers are needed so that DNA polymerase can start replication.

Question 5

What is a primer?

Answer 5

A primer is a short strand of nucleotides that binds to the 3’ end of the DNA template strand.

Question 6

State the function of a DNA polymerase?

Answer 6

The enzyme DNA polymerase adds DNA nucleotides, using complementary base pairing to the deoxyribose 3’ end of the new DNA strand that is forming.