what is meant by chemical basis of heredity?
The genetic substance of all living creatures, from viruses to man is a complex chemical compound - the nucleic acid DNA (deoxyribonucleic acid). The instructions in DNA are transmitted by messenger RNA (ribonucleic acid).
Chromosomes are made from DNA. Genes are short sections of DNA. DNA carries the genetic code that determines the characteristics of a living thing. A gene is a short section of DNA. Each gene codes for a specific protein by specifying the order in which amino acids must be joined together. The cells nucleus contains chromosomes made from long DNA molecules.