1. AP BIOLOGY DNA History & Structure

2. Nucleic Acid Structure

3. Complimentary Base Pairing

4. Frederick Griffith

5. FREDERICK GRIFFITH EXPERIMENT Living S cells (control) Living R cells (control) Heat-killed S cells (control) Mixture of heat-killed S cells and living R cells Mouse dies Living S cells are found in blood sample Mouse healthy Mouse dies RESULTS

6. Oswald Avery

7.  Avery and group identified the transforming substance was DNA. His colleagues were McCarty and MacLeod.

8. Alfred Hershey & Martha Chase

9. Bacteriophage injecting its DNA into a bacterial cell

10. Electron Microscope View

11. Hershey – Chase Experiment

12. Erwin Chargaff

13. CHARGAFF’S RULE Adenine = Thymine (DNA) or Uracil (RNA) & Guanine = Cytosine If you know the % composition of 1, you can find the % composition of the other 3.

14. Rosalind Franklin

15. DNA from a top view

16. DNA from a side view

17. James Watson & Francis Crick with their DNA model

18. See the HYDROGEN bonds?