1. Nucleic acids are biopolymers of nucleotides
Controlled hydrolysis of DNA and RNA yields three components namely a nitrogeneous base, a pentose sugar and phosphate group.
2. Nitrogen base
(a) These are nitrogen containing organic compounds which are derivatives of two parent compounds, pyrimidine and purine.
(b) Both DNA and RNA have two major purine bases, adenine (A) and guanine (G). In both DNA and RNA, one of the pyrimidines is cytosinc (C), but the second pyrimidine is thymine (T) in DNA and uracil (U) in RNA.
3. Pentose Sugar
Nucleic acids have two types ofpentoses. The recurring deoxyribonucleotide units of DNA contain 2’ – dcoxy – D – ribose and the ribonucleotide units of RNA contain D – ribose. In nucleotides, both types of pentoses are in their – furanose form.
4. Phosphate group
Phosphoric acid forms phosphor diester bond between nucleotides. Based on the number of phosphate group present in the nucleotides, they are classified mono nucleotide, dinucleotide and trinucleotide.
5. The molecule without the phosphate group is called a nucleoside. A nucleotide is derived from a nucleoside by the addition of a molecule of phosphoric acid.
6. Sugar + Base → Nucleoside
Nucleoside + Phosphate → Nucleotidc
Nucleotide → Polynucleotide (Nucleic Acid)
