Mendel while explaining the result of his breeding experiment pointed out that hereditary characters were governed by some particular genetic determines present in the germ cells. These genetic determines of hereditary character are now called "genes". The term gene was coined by Prominent Geneticist Johansen Dauries (1990) used the term 'pangen' and perhaps from this word the term 'gene' was derived. In old books of genetics the term 'gene' is treated as merely something which effects the phenotype and behaves as a particle. It should be noted here that nothing was said about the size, shape and chemical constitution of gene in old definition:
As per 'Morgan' theory of gene it is stated that:
- chromosomes are bearers of hereditary units and each chromosome carries hundreds or thousands of genes.
- The genes are arranged on the chromosomes in linear order and on specific region or loci.