1. Structure Of Adenine

2. Structure of guanine

3. Cytosine

4. Thymine

5. Uracil

6. Adenine nucleoside and nucleotide

7. Pyrimidine nucleoside

8. Primary structure of DNA

9. Secondary Structure of DNA

10. Secondary structure of DNA

11. Syn and anti form of nucleoside

12. FORCES THAT STABILIZE NUCLEIC ACID STRUCTURES
SUGAR-PHOSPHATE CHAIN CONFORMATIONS
BASE PAIRING
BASE-STACKING,HYDROPHOBIC
IONIC INTERACTIONS

13. BASE-PAIRING WATSON-CRICK GEOMETRY HOOGSTEEN GEOMETRY
THE A-T PAIRS USE ADENINE’S N1 AS THE H-BOND ACCEPTOR
HOOGSTEEN GEOMETRY
N7 IS THE ACCEPTOR
SEEN IN CRYSTALS OF MONOMERIC A-T BASE PAIRS
IN DOUBLE HELICES, W-C IS MORE STABLE
ALTHOUGH HOOGSTEIN IS MORE STABLE FOR A-T PAIRS, W-C IS MORE STABLE IN DOUBLE HELICES
CO-CRYSTALLIZED MONOMERIC G-C PAIRS ALWAYS FOLLOW W-C GEOMETRY
THREE H-BONDS

14. IN MOST DOUBLE-HELICAL STRUCTURES, ALL BASES IN ANTI FORM

16. Hydrogen bonding between A and T

17. Hydrogen bonding between G and C