Question

The given segment of parental DNA is undergoing replication.
5’ AATCGCTTTAAAC 3’
3’ TTAGCGAAATTTG 5’
Predict the sequence of the newly synthesized daughter strands.

• A. Two molecules of 5’ AATCGCTTTAAAC 3’
  3’ TTAGCGAAATTTG 5'
• B. Two molecules of 5’ AATCGCTTTTTTG 3’
  3’ TTAGCGAAAAAAC 5'
• C. One molecule of 5’ AATCGCTTTAAAC 3’
  3’ TTAGCGAAATTTG 5'
• D. One molecule of 5’ AATCGCTTTAAAC 3’
  3’ AATCGCTTTAAAC 5'

Answer 1

The correct option is A Two molecules of 5’ AATCGCTTTAAAC 3’

3’ TTAGCGAAATTTG 5'
During the replication of DNA, the hydrogen bonds present between the strands of the parental DNA molecule get broken down at the origin of replication due to the action of helicase. A replication fork is formed and gradually, the fork moves in both directions to ensure strand separation. On the separated single stranded parental DNA, complementary strands are synthesized by the enzyme DNA polymerase. Hence, replication of one double stranded DNA molecule yields two new molecules, each having one parental strand and one daughter strand/ newly synthesized strand. Both the newly synthesised molecules of DNA will be identical to the parental DNA.