The discovery of DNA its self was 60 years before proven by Dr. Griffith. It was discovered by Swiss scientist F.Miescher. The name nucleic acid in deoxyribonucleic acid (DNA) comes from acidic substances contained in the nucleus.
DNA, formally called deoxyribonucleic acid, is one of the nucleic acids that form genes. DNA molecules are a double helix structure, made from two long strands of sugar and phosphate molecules creating a spiral around the same axis. This double helix structure was discovered by James Watson and Francis Crick.
DNA is formed from three parts: nitrogenous bases, phosphate molecules, and sugar made from deoxyribose. Bases are the components of DNA or RNA. With these three parts as one unit, units are repeated to form what we all DNA. There are no differences in the kind of sugar and phosphate molecules included in these units, but there are four kinds to the bases: Adenine (A), thymine (T), cytosine (C), and guanine (G). The bases of adenine and guanine are called purines, and the bases of thymine and cytosine are called pyrimidines. Purines are formed from two rings; a heptagon and a pentagon, and pyrimidines from a single heptagon. This means that prines are larger than pyrimidines.
Next are units called nucleotides, each composed of one nitrogenous base (in the picture below, adenine), and one sugar. The formal name for this unit is deoxyadenothine, but usually is shortened to dA. The same with the others- dT for deoxythymine, dG for deoxyguanothine, and dC for deoxycytosine.
The next picture is one strand of DNA. This is made from nucleotides (nitrogenous base+sugar) and nucleotides with phosphate in between. The arrows show which way the links of DNA lengthens by enzymes etc. Usually, arrows move from 5' to 3'. The numbers 5' and 3' are the numbers put on the pentagon shaped sugars.