Biology NUCLEIC ACIDS (DNA)

Nucleic Acids

`->` F. Meischer discovered nucleic acid in nucleus of pus cell and called it "nuclein". The term nucleic acid was coined by "Altman."

`->` Nucleic acids are polymer of nucleotides.
= Nitrogen base + pentose sugar + phosphate
On the basis of structure nitrogen bases are broadly of two types

1. Pyrimidines - Consist of one pyrimidine ring. Skeleton of ring composed of two nitrogen and four Carbon
atoms. e.g. Cytosine, Thymine and Uracil.

2. Purines - Consist

Consist of two rings i.e. one pyrimidine ring `(2N + 4C)` and one imidazole ring `(2N + 3C)` e.g.
Adenine and Guanine.

Pentose Sugar :-

Nitrogen base forms bond with first carbon of pentose sugar to form a nucleoside. Nitrogen of first place
`(N_3)` forms bond with sugar in case of pyrimidines while in purines nitrogen of ninth place `(N_2)` forms bond
with sugar.
Phosphate forms ester bond (covalent bond) with fifth Carbon of sugar to form a complete nucleotide.

Types Of Nucleosides and Nucleotides

1. Adenine + Ribose = Adenosine
Adenosine + Phosphate = Adenylic acid (AMP)

2. Adenine + Deoxyribose = Deoxy adenosine
Deoxy adenosine + P = Deoxy adenylic acid (dAMP)

3. Guanine + Ribose = Guanosine
Guanosine + P = Guanylic acid (GMP)

4. Guanine + Deoxyribose Deoxy guanosine
Deoxy guanosine + P = Deoxy guanylic acid (dGMP)

5. Cytosine + Ribose = Cytidine
Cytidine + P = Cytidylic acid (CMP)

6. Cytosine + Deoxyribose = Deoxycytidine
Deoxycytidine + P = Deoxycytidylic acid (dCMP)

7. Uracil + Ribose = Uridine
Uridine + P = Uridylic acid (UMP)

8. Thymine + Deoxyribose = Deoxy thymidine
Deoxythymidine + P = Deoxythymidylic acid (dTMP)