Genes are the central concept of the heredity science, genetics. If genes are physical particles, like other cell components, they must be made of molecules and it should therefore be possible to study them directly by biophysical and biochemical methods. This led to a new branch of genetics called Molecular Biology. Genetics and molecular biology are very closely related subjects and although there is a distinction between them there are more similarities.

For this reason, the term molecular genetics is now often used to describe that branch of biology concerned with the study of all aspects of genes. The initial aim of molecular genetics was the identification of the chemical nature' of the gene. This new approach led to new concepts, and soon biologists ceased to regard individual genes simply, units of inheritance and instead began to look on them as biological information with the entire complement.

Genes in an organism contain the total amount of information needed to construct a living, functioning body of that organism. Genes themselves are the instructions for making other biomolecules. Hence to understand the structure and functions of genes as molecules, we must understand the qualifications or prerequisites a molecule must have to qualify as genetic materials