Question

Assertion (A): The sugar-phosphate backbone of two chains in DNA double helix shows anti-parallel polarity.
Reason (R): The phosphor-diester bonds in one strand go from a 3’ carbon of one nucleotide to a 5’ carbon of adjacent nucleotide, whereas those in complementary strand go vice versa.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
• C. (A) is true, but (R) is false.
• D. (A) is false, but (R) is true.

Hint:

The anti-parallel arrangement of DNA strands is essential for complementary base pairing and replication.

Answer 1

The Correct Option is A

\begin{itemize} \item DNA strands exhibit anti-parallel orientation; one proceeds from 5' to 3', while its complementary strand runs from 3' to 5'. \item The arrangement of phosphor-diester bonds, as detailed in Reason (R), accounts for the anti-parallel polarity of DNA strands, thereby validating the explanation provided in Assertion (A).\end{itemize}% Quick tip