1. Molecular Biology of the Gene DNA

2. Identification of Genetic Material Identification of Genetic Material Structure of DNA Structure of DNA DNA Replication DNA Replication

3. Genetic Material –DNA or Protein? Bacteriophage Replication Bacteriophage Replication Martha Chase and Alfred Hershey (1952)

4. Roles of the Genetic Material “A genetic material must carry out two jobs: duplicate itself and control the development of the rest of the cell in a specific way.” -Francis Crick

5. Hershey and Chase Experiment

6. Bacterial Transformation Frederick Griffith, 1928 Diplococcus pneumoniae infects mice Diplococcus pneumoniae infects mice Mice develop pneumonia and die Mice develop pneumonia and die Two types of bacteria: R bacteria rough coat  no pneumonia R bacteria rough coat  no pneumonia S bacteria smooth coat  pneumonia S bacteria smooth coat  pneumonia Coat type is associated with virulence. Coat type is associated with virulence.

7. Griffith’s Experiments Figure 9.1

8. The “Transforming Principle” Avery, MacLeod, and McCarty, 1944 Treated lysed S bacteria with protease and DNase DNase prevented transformation Therefore DNA is the transforming principle Figure 9.2

9. Monomers and Polymers Polymers are made up of monomers Polymers are made up of monomers Mono = one Mono = one Poly = many Poly = many For example: For example: Proteins are made up of amino acids

10. Polynucleotides Polynucleotides are made up of nucleotides Polynucleotides are made up of nucleotides Sugar-phosphate backbone Phosphate group Nitrogenous base Sugar DNA nucleotide DNA polynucleotide DNA nucleotide Sugar (deoxyribose) Thymine (T) Nitrogenous base (A, G, C, or T) Phosphate group A C T G T T G T C A

11. Basic Structure of a Nucleotide Phosphate Group Nitrogenous Base Sugar

12. Nitrogenous Bases (DNA) Thymine (T) Cytosine (C) Adenine (A) Guanine (G) Pyrimidines One Ring Purines Two Rings

13. And the Nobel Prize Goes To… Physiology or Medicine 1962 "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material" Physiology or Medicine 1962 "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material" Rosalind Franklin (1920-1958)Watson and Crick with their model of DNA

14. Rope Ladder Model

15. Sugar and Phosphate Backbone Nitrogenous Base Pairs Rope Ladder Model

16. Complementary Base Pairs A-T A-T G-C G-C

17. DNA: The Double Helix Hydrogen bond Base pair Ribbon model Partial chemical structure Computer model G C TA A T T A C C G G G C T T T T A A A A GC A T A C T G CG A T

18. Orientation of DNA The 5’ phosphate of one nucleotide is attached to the 3’ hydroxyl group of the previous nucleotide The directionality of a DNA strand is due to the orientation of the phosphate-sugar backbone Figure 9.11

19. Structure of DNA Structure of DNA DNA Replication DNA Replication DNA vs. RNA DNA vs. RNA

20. Chromosomes and Mitosis

21. Chromosomes Are Made of DNA

22. DNA Replication DNA Replication is Semiconservative DNA Replication is Semiconservative Parental molecule of DNA Both parental strands serve as templates Two identical daughter molecules of DNA T Nucleotides CG A GC A A T T A A A A C C C T T G G A C A A A A A A CC C CG T G T T T T G T T T G G Each new double helix contains one parental strand and one daughter strand

23. G C T A A T G G C C T T A A C C G G G G C C G G G C C C T T T T T C A A A A A G T G C A T T T T A A A A

24. An enzyme “unzips” DNA Replication Bubble

25. Origin of replication Bubble Parental strand Daughter strand Two daughter DNA molecules Replication Bubbles

26. 3 end 5 end 3 end P 4 A T C G HO OH P 1 3 2 5 P P P P C G P P A T P 4 3 1 2 5 DNA is synthesized from 5 ’ to 3 ’ One Little Problem…

27. DNA polymerase molecule Parental DNA 3 5 3 5 5 3 LEADING STRAND Daughter strand synthesized continuously LAGGING STRAND Daughter strand synthesized In pieces DNA Polymerase Can Only Move 5 ’ to 3 ’ DNA polymerase adds nucleotides to the 3 ’ end “ase” = enzyme

28. DNA Ligase 3 5 DNA ligase 3 5 LEADING STRAND LAGGING STRAND DNA ligase “glues” the fragments together

29. Structure of DNA Structure of DNA DNA Replication DNA Replication DNA vs. RNA DNA vs. RNA

30. Nitrogenous Bases (DNA and RNA) Thymine (T) Cytosine (C) Adenine (A) Guanine (G) H Uracil (U) Pyrimidines One Ring Purines Two Rings

31. DNA vs. RNA Deoxyribonucleic Acid Ribonucleic Acid H OH Phosphate Group Ribose Phosphate Group Deoxyribose Nitrogenous Bases TCAG UCAG Nitrogenous Base CH 3 H Thymine Uracil