Question

Match List-I with List-II

Choose the correct answer from the options given below:

• (A) - (II), (B) - (III), (C) - (I), (D) - (IV)
• (A) - (II), (B) - (I), (C) - (III), (D) - (IV)
• (A) - (II), (B) - (I), (C) - (IV), (D) - (III)
• (A) - (II), (B) - (IV), (C) - (I), (D) - (III)

Hint:

To solve this easily: Associate Z-DNA with the left-handed zigzag shape formed by alternating purine-pyrimidines under high salt (IV), and B-DNA with the common in vivo state (II).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
DNA can assume different conformations (structural isoforms) depending on factors such as hydration levels, salt concentrations, and local sequence symmetry.

Step 2: Detailed Explanation:
Let us analyze and pair each DNA conformation with its corresponding description:
(A) B-DNA is the standard right-handed double-helical structure described by Watson and Crick, which represents the most common and physiologically relevant form found in vivo (II).
(B) A-DNA is a shorter and wider right-handed double helix that is observed under partially dehydrated (desiccated) conditions in vitro (I).
(C) Z-DNA is a left-handed double helix characterized by a zigzag phosphodiester backbone. It is favored by alternating purine-pyrimidine tracts under high-salinity conditions (IV).
(D) H-DNA is an atypical triple-stranded helical structure formed by sequences containing polypurine-polypyrimidine segments with mirror-repeat symmetry (III).
This gives the match combination: (A)-(II), (B)-(I), (C)-(IV), (D)-(III).

Step 3: Final Answer:
This matching is found in option (C).