Question

Nucleotide pairs present in one turn of DNA helix

• A. $9$
• B. $8$
• C. $20$
• D. $10$

Answer 1

The correct option is D $10$

Watson and Crick Model of DNA double helix
According to Watson and Crick’s model of double helical DNA -
One turn of DNA helix has $10$ nucleotides or $10$ base pairs.Length of one complete turn of the DNA double helix is $34Å=3.4nm$.
Length between two adjacent base pairs $=\left(3.4/10\right)nm=0.34nm$.