Question

(a) Draw a labelled diagram of a “replicating fork” showing the polarity. Why does DNA replication occur within such ‘forks’? 

(b) Name two enzymes involved in the process of DNA replication, along with their properties.

Answer 1

(a)

The two strands of DNA cannot be separated in its entire length due to very high energy requirement. High amount of energy is required to break the hydrogen bonds holding the two strands. Therefore, the replication occurs in small opening of DNA strands called the replication fork. 

(b) 

i. DNA dependent DNA polymerase: adds nucleotides only in 5 to 3 directions. 

ii. DNA ligase: joins the discontinuously synthesised DNA fragments during replication.