Definition of Base Pair

Base pairs are the two nitrogenous bases that are bonded with one another and form the ladder of the DNA molecule. The DNA is composed of two strands that run in antiparallel directions to each other and are wound around to give a structure as of a twisted ladder. The backbone of the strand is made up of deoxyribose sugar and phosphate groups.

There are four nitrogenous bases and they are divided into two types i.e. purines (double-ringed) and pyrimidines (single ringed). Adenine and guanine are the purines whereas cytosine and thymine are pyrimidines. These bases are attached to the deoxyribose. The hydrogen bonds are the tool that holds the two strands together.

Two hydrogen bonds link adenine with thymine and hence a base pair is formed. One the other hand, the base pair of cytosine and guanine share three hydrogen bonds. The human genome is composed of 3M base pairs.