DNA is the abbreviated form of Deoxyribonucleic acid. It is present in the form of chromosomes. Chromosomes are present in the nucleus of every cells. DNA is passed on to the offsprings through gametes from the parental generation. DNA is a doubled helical structure having nucleotides. These nucleotides are made of deoxyribose sugar, phosphoric acid and nitrogenous bases such as adenine thymine, cytosine and guanine. James D. Waston and Francis Crick proposed the double helix or spiral stair case structure of DNA molecule in 1953. They were awarded the Nobel Prize for this discovery.