DNA Structure and Replication - Medical Science

Q1:

In DNA double helix, the two DNA chains are held together by

A covalent bonds between the pair of bases

B hydrogen bonds between the pair of bases

C ionic bonds between the pair of bases

D none of the above

ANS:B - hydrogen bonds between the pair of bases

Bases are pair by hydrogen bond adenine & thymine by 2 hydrogen bond, cytosine & guanine by 3 hydrogen bond.