Question

The polarity of the DNA strands from a to b and from c to d shown during replicating shown in the figure below would be:

• A. $\text{a} - \text{b} \to 3^{'} - 5^{'}$
  $\text{c} - \text{d} \to5^{'} - 3^{'}$
• B. $\text{a} - \text{b} \to3^{'} - 5^{'}$
  $c - \text{d} \to 3^{'} - 5^{'}$
• C. $\text{a} - \text{b} \to 5^{'} - 3^{'}$
  $\text{c} - \text{d} \to 3^{'} - 5^{'}$
• D. $\text{c} - \text{d} \to 5^{'} - 3^{'}$
  $\text{c} - \text{d} \to5^{'} - 3^{'}$

Answer 1

Answer: (A)

DNA polymerases required for the DNA replication can catalyse polymerization in only one direction that is $5'$ to $3'$ Thus, on one strand (the template with polarity $3'$ to $5'$), the replication is continuous, while on the other (the template with polarity $5'$ to $3'$), it is discontinuous.