1. DNA as the Genetic material
Early 20th century – each animal has a unique set of molecules
Mid-20th century – all life has common molecules- sugar, fats, proteins, nucleic acids
Many scientists believed protein to be best candidate for genetic material – most complex structure

2. Figure 16.1 Transformation of bacteria
Link to DNA interactive
Link to animation

4. DNA vs. Protein as Genetic Material
Avery and McCloud (1944) – transforming material is destroyed by adding DNAase, not affected by protease.
Some researchers still believed that convinced protein impurities not DNA was the genetic material
1952 – Hershey-Chase to settle protein vs. DNA question

5. Figure 16.2a The Hershey-Chase experiment: phages

6. Figure 16.2ax Phages

7. Figure 16.2b The Hershey-Chase experiment

8. Link to Hershey-Chase animation

9. Timeline
1928-Griffith – there is a chemical substance that can be transferred to bacteria changing its genetic characteristics
1944- Avery and McCloud – transforming substance is DNA
1952 – Hershey-Chase experiment-only DNA and not protein are transferred to bacteria during phage infection

10. Figure 16.0 Watson and Crick
Watson BP Link
HHMI Video
Nova 51

11. (b) Franklin’s X-ray diffraction photograph of DNA
Fig. 16-6
(a) Rosalind Franklin
(b) Franklin’s X-ray diffraction photograph of DNA

12. Franklin Tobacco Mosaic Structure

13. Unnumbered Figure (page 292) Purine and pyridimine

14. Figure 16.5 The double helix

15. Figure 16.3 The structure of a DNA stand

16. Figure 16.12 The two strands of DNA are antiparallel

17. Figure 16.6 Base pairing in DNA

18. Figure 16.7 A model for DNA replication: the basic concept (Layer 1)

19. Figure 16.7 A model for DNA replication: the basic concept (Layer 2)

20. Figure 16.7 A model for DNA replication: the basic concept (Layer 3)

21. Figure 16.7 A model for DNA replication: the basic concept (Layer 4)

22. Figure 16.8 Three alternative models of DNA replication

23. Figure 16.8 Three alternative models of DNA replication

24. Figure 16.9 The Meselson-Stahl experiment tested three models of DNA replication (Layer 1)

25. Figure 16.9 The Meselson-Stahl experiment tested three models of DNA replication (Layer 2)

26. Figure 16.9 The Meselson-Stahl experiment tested three models of DNA replication (Layer 3)

27. Figure 16.9 The Meselson-Stahl experiment tested three models of DNA replication (Layer 4)

30. Link to Meselson-Stahl Animation
Link to Sumanas