4 . Ribonucleotide Phosphate unit + Ribose + one base unit from A , G , C , or U .
5 . Deoxyrlbo nucleotide Phosphate unit + Deoxyribose + one base from A , G , C or T .
6 . Nucleoside Ribose- / deoxyribose + one base unit from A , G , C , Tor U .
DNA and RNA
Nucleic acid is polynucleotide , present in the living cells or bacterial cells having no nucleus and in viruses having no cells .
( i ) DNA Deoxy ribonucleic acid . DNA + H2O → Phosphoric acid + deoxyribose + A , G , C , T
( ii ) RNA Ribonucleic acid RNA + H2O → Phosphoric acid + Ribose + A , G , C , U
Structure of DNA
It consists of two polynucleotide chains , each chain form a right handed helical spiral with ten bases in one turn of the spiral . The two chains coil to double helix and run in opposite direction . These are held together by hydrogen bonding .
Structure of RNA
It is usually a single strand of ribonucleotides and take up right handed helical conformation . Up to 12000 nucleotides constitute an RNA .