1. II) The History of DNA

2. Material of Heredity Friedrich Misechner (1869)  isolated white substance he called nuclein  contained both protein and DNA/RNA Joachim Hammerling (1943)  demonstrated that the nucleus contained heredity material

3. Phoebus Levene (1910) first to isolate the two type of nucleic acid (DNA and RNA) showed chromosomes are made up of DNA and protein Frederick Griffith (1920s) transforming principle  showed that pathogenic bacteria can still spread diseases even when dead. you have kill the bacteria and destroy the DNA to stop the bacteria. DNA can transform non pathogenic bacteria in pathogenic bacteria.  shows DNA is a hereditary material

5. Hershey and Chase (1952) gave definitive proof that DNA was the material of heredity and not protein.

6. Chargaff’s Rule (1950) discovered that nucleotides are present in varying, but characteristic, proportions.  in DNA the amount of adenine is always approximately equal to the amount of thymine (A ~ T) the amount of cytosine is always approximately equal to the amount guanine. (C ~ G)

7. James Watson and Francis Crick (1953) worked out the structure of DNA using data from: Rosalind Franklin (Maurice Wilkins)- x-ray diffraction Chargaff’s rule

8. III) DNA REPLICATION

9. I) DNA Structure and Replication DNA Replication for mitosis and meiosis to occur the DNA must make an exact copy itself first (S Phase of interphase) for every chromosome  result: 2 identical sister chromatids attached at the original centromere  this is called DNA replication the main stages of DNA replication is the same in prokaryotic and eukaryotic cells. DNA replication is semiconservative B) DNA Replication

11. EXPERIMENT RESULTS CONCLUSION 1 2 4 3 Conservative model Semiconservative model Dispersive model Bacteria cultured in medium containing 15 N Bacteria transferred to medium containing 14 N DNA sample centrifuged after 20 min (after first application) DNA sample centrifuged after 40 min (after second replication) More dense Less dense Second replicationFirst replication B) DNA Replication

12. EXPERIMENT RESULTS 1 3 2 4 Bacteria cultured in medium containing 15 N Bacteria transferred to medium containing 14 N DNA sample centrifuged after 20 min (after first application) DNA sample centrifuged after 20 min (after second replication) Less dense More dense B) DNA Replication

13. Fig. 16-11b CONCLUSION First replicationSecond replication Conservative model Semiconservative model Dispersive model B) DNA Replication

14. ex. CHROMOSOME #18 not replicated yet CHROMOSOME #18 now replicated! centromere one sister chromatid identical sister chromatid

15. #18

16. A T G C TA TA G C (a) Parent molecule B) DNA Replication I) DNA Structure and Replication

17. 4 steps to DNA SEMI-CONSERVATIVE REPLICATION 1. “unzipping” HELICASE ENZYME breaks the HYDROGEN BONDS between the NITROGEN BASE PAIRS ex. chromosome #18 A T C G

18. Fig. 16-9-2 A T G C TA TA G C A T G C T A T A G C (a) Parent molecule (b) Separation of strands B) DNA Replication I) DNA Structure and Replication

19. 2. “attaching” POLYMERASE ENZYME joins free-floating COMPLEMENTARY NUCLEOTIDES to the original strand of DNA A with T, C with G look! 2 new strands of DNA are being formed from the original DNA! RED = original DNA BLACK = new strand of DNA being formed! A T C G T A G C

20. A T G C TA TA G C (a) Parent molecule AT GC T A T A GC (c) “Daughter” DNA molecules, each consisting of one parental strand and one new strand (b) Separation of strands A T G C TA TA G C A T G C T A T A G C B) DNA Replication I) DNA Structure and Replication

21. I) DNA Structure and Replication

22. 3. “proofreading” PROOFREADER ENZYMES FIX any MISMATCHED BASE PAIRS prevents mutations! proofreader enzymes are actually other polymerase enzymes

23. 4. “final result” 2 IDENTICAL SISTER CHROMATIDS joined at the ORIGINAL CENTROMERE note that each sister chromatid is “half-old, half-new” (SEMI-CONSERVATIVE!)

24. DNA REPLICATION

25. Fun Game! http://nobelprize.org/educational_games/medicine/d na_double_helix/ http://nobelprize.org/educational_games/medicine/d na_double_helix/ Note: There are an estimated 3 billion base pairs in the HUMAN GENOME. Trivia: Replication occurs at a speed of 50 nucleotides per second!