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. $\text{a}-\text{b}\to 3^{{}^{\prime }}-5^{{}^{\prime }}$
  $\text{c}-\text{d}\to 5^{{}^{\prime }}-3^{{}^{\prime }}$
• B. $\text{a}-\text{b}\to 3^{{}^{\prime }}-5^{{}^{\prime }}$
  $c-\text{d}\to 3^{{}^{\prime }}-5^{{}^{\prime }}$
• C. $\text{a}-\text{b}\to 5^{{}^{\prime }}-3^{{}^{\prime }}$
  $\text{c}-\text{d}\to 3^{{}^{\prime }}-5^{{}^{\prime }}$
• D. $\text{c}-\text{d}\to 5^{{}^{\prime }}-3^{{}^{\prime }}$
  $\text{c}-\text{d}\to 5^{{}^{\prime }}-3^{{}^{\prime }}$

Answer 1

Answer: (A)

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