Which of the following statements describing the WatsonCrick

Which of the following statements describing the Watson-Crick model for DNA structure is INCORRECT?

A. DNA has two grooves running helically along its length, one of which is wider than the other.

B. The base-paired polynucleotide chains have antiparallel directions.

C. The classic Watson-Crick hydrogen bonding between AT and GC pairs is found in Z-DNA.

D. One turn of the double helix involves approximately 10 nucleotides.

E. The helical structure is stabilized entirely by hydrogen bonding.

Solution

Answer: C. The classic Watson-Crick hydrogen bonding between AT and GC pairs is found in Z-DNA.

Reason:

Watson and Crick model of DNA structure in 1953 research paper has revealed that DNA is a nucleotide polymer (hydrogen bonds between adenine and thymine; Guanine and cytosine) and possesses double helical structure in which sugar & phosphate units of two strands are winding together around the central axis and running anti-parallel to each other. The stability of the B-DNA is acquired by the presence of hydrogen bonds with the stacking interactions (pi-pi) between base pairs AT & GC and this was meticulously proposed by Watson & Crick in their double helical model. DNA has two grooves running helically along its length, one of which is wider than the other. The base-paired polynucleotide chains have antiparallel directions. One turn of the double helix involves approximately 10 nucleotides. The helical structure is stabilized entirely by hydrogen bonding.