1. Model Building of DNA

2. Early efforts to make a DNA model

3. Watson’s
Early attempt
To create Double Helix

4. Jerry Donohue:
Worked on dNTPs
Told Watson that
It was the Keto form
Found under physiological
conditions

6. B-DNA

7. B-DNA

23. STACKING OF BASES

24. A-DNA, B-DNA and Z-DNA
The Z-DNA helix is left-handed and has a structure that repeats every 2 base pairs.
The major and minor grooves, unlike A- and B-DNA, show little difference in width

25. B-DNA and Z-DNA

26. A-DNA, B-DNA and Z-DNA

27. Lambda repressor

28. EcoRV