1. A Short History of DNA Technology

2. The History Of DNA

3. Miescher

4. 1869 removed substance from pus off of old bandages had acid properties, came from nucleus called it “nucleic acid”

5. Griffith

6. 1865 1928 - Frederick Griffith Bacterial Strain Injection Results Living S cells Living R cells Heat killed S cells Heat killed S cells mixed with living R cells Living S cells in blood sample from dead mouse capsule Transformation of Streptococcus pneumoniae “Rough” colonies“Smooth” colonies

7. Griffith smooth and rough bacteria dead smooth could “transform” live rough cells “accidental” discovery

8. Avery, MacLeod, McCarty

9. 1865 1944 - Avery, MacLeod & McCarty Purified DNA as transforming factor Oswald Avery Work not well-received Protein more complex & better able to store information Colin MacLeodMaclyn McCarty

10. Avery, McLeod, McCarty separated cellular molecules tested each for “transforming” abilities carbohydrates, lipids, proteins were ineffective only nucleic acids “transformed” the cells

11. Hershey and Chase

12. 1865 1952 - Hershey & Chase Viral DNA (not protein) programs cells Martha Chase & Alfred Hershey Bacteriophages

13. 1865 1952 - Hershey & Chase T2 Phage Bacterium Radioactive protein ( 35 S) Radioactive phage infects bacterial cells Blender separates protein coats from bacterial surface Centrifuge and measure radioactivity in pellet and supernatant Radioactivity in supernatant, but not pellet

14. 1865 1952 - Hershey & Chase Radioactive DNA ( 32 P) Radioactivity in pellet, but not supernatant Therefore, it is the viral DNA, and not protein, that programs cells to make copies of the virus.

15. Hershey and Chase chose “organism” composed only of protein and nucleic acid infected cells with viruses tagged with radioisotopes tagged proteins were not transferred tagged nucleic acids were transferred

16. Chargaff

17. 1865 1947 - Erwin Chargoff DNA bases follow certain “rules” Base composition is species specific A = T, C = G for all species

18. Chargaff analyzed percentage of each base in DNA samples found adenine % = thymine% found cytosine % = guanine %

19. Wilkins and Franklin

20. 1865 1953 - Franklin & Wilkins Elucidation of the helical nature of DNA X-ray source Crystallized DNA Rosalind Franklin Maurice Wilkins Photographic film

21. Wilkins and Franklin X-ray crystallography on DNA to establish shape, dimensions of molecule

22. Watson and Crick 1953

23. 1953 - Watson & Crick 1865 Description of the 3-D structure of DNA Francis Crick & James Watson

24. Watson and Crick did no original research/ relied on work of others analyzed X-ray crystallography, biochemistry hypothesized double-stranded helix in 1953

25. 1953 - Watson & Crick 1865 What they deduced from: Franklin’s X-ray data Double helix Uniform width of 2 nm Bases stacked 0.34 nm apart Chargoff’s “rules” Adenine pairs with thymine Cytosine pairs with guanine

26. 1953 - Watson & Crick 1865 What they came up with on their own: Bases face inward, phosphates and sugars outward Hydrogen bonding Hinted at semi-conservative model for replication

55. Review of Gel Electrophoresis and DNA Fingerprinting Write questions and answers in your notes 1)What section of the DNA molecule is used for DNA fingerprinting? 2)How is the DNA polymer cut? 3) What factors determine how fast a segment of DNA migrates in the gel? 4) What is the purpose of the marker?