Question

State whether the following statement is true or false.

All DNA polymerases can only extend polynucleotide chains; they cannot initiate new chains.

Answer 1

This statement is true.

Explanation:

DNA polymerases require a free 3’-OH group to attach the next nucleotide, meaning they can only add onto an existing strand. Because they cannot start a new chain from scratch, an enzyme called primase must first synthesise a short RNA primer. Once this primer provides a starting point, DNA polymerase can extend the polynucleotide chain.