– At the time of Mendel, the nature of 'factors' regulating the pattern of inheritance was not clear. Over the next hundred years, the nature of the putative genetic material was investigated culminating in the realisation that $DNA $- deoxyribonucleic acid – is the genetic material. Nucleic acids are polymers of nucleotides.

Deoxyribonucleic acid ($DNA$) and Ribonucleic acid ($RNA$) are the two types of nucleic acids found in living systems.

$DNA$ acts as the genetic material in most of the organisms.

$RNA$ though it also acts as a genetic material in some viruses, mostly functions as messenger. $RNA$ has additional roles as well.

It functions as adapter, structural and in some cases as a catalytic molecule.