The document summarizes key discoveries in establishing DNA as the genetic material. It describes experiments by Griffith, Avery, Hershey and Chase showing that DNA transforms bacteria and is the genetic material in viruses. Watson and Crick developed the double helix model of DNA structure based on Franklin's X-ray images, explaining Chargaff's rules. Their model suggested DNA replication is semiconservative, supported by Meselson-Stahl experiments. DNA polymerase synthesizes new DNA strands while helicase and ligase aid replication.

1. Chapter 16 The Molecular Basis of Inheritance

5. Fig. 16-2 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 Mouse dies Mouse healthy Mouse healthy Living S cells RESULTS EXPERIMENT

9. Fig. 16-3 Bacterial cell Phage head Tail sheath Tail fiber DNA 100 nm

12. Fig. 16-4-3 EXPERIMENT Phage DNA Bacterial cell Radioactive protein Radioactive DNA Batch 1: radioactive sulfur ( 35 S) Batch 2: radioactive phosphorus ( 32 P) Empty protein shell Phage DNA Centrifuge Centrifuge Pellet Pellet (bacterial cells and contents) Radioactivity (phage protein) in liquid Radioactivity (phage DNA) in pellet

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

18. Fig. 16-7b (c) Space-filling model

19. Fig. 16-7a Hydrogen bond 3  end 5  end 3.4 nm 0.34 nm 3  end 5  end (b) Partial chemical structure (a) Key features of DNA structure 1 nm

21. Fig. 16-UN1 Purine + purine: too wide Pyrimidine + pyrimidine: too narrow Purine + pyrimidine: width consistent with X-ray data

25. Fig. 16-8 Cytosine (C) Adenine (A) Thymine (T) Guanine (G)

29. Fig. 16-9-3 A T G C T A T A G C (a) Parent molecule A T G C T A T A G C (c) “Daughter” DNA molecules, each consisting of one parental strand and one new strand (b) Separation of strands A T G C T A T A G C A T G C T A T A G C

33. Fig. 16-10 Parent cell First replication Second replication (a) Conservative model (b) Semiconserva- tive model (c) Dispersive model

37. Fig. 16-11 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 replication First replication

41. Fig. 16-16 Overview Origin of replication Leading strand Leading strand Lagging strand Lagging strand Overall directions of replication Template strand RNA primer Okazaki fragment Overall direction of replication 1 2 3  2 1 1 1 1 2 2 5  1 3  3  3  3  3  3  3  3  3  5  5  5  5  5  5  5  5  5  5  5  3  3 

44. Fig. 16-12 Origin of replication Parental (template) strand Daughter (new) strand Replication fork Replication bubble Two daughter DNA molecules (a) Origins of replication in E. coli Origin of replication Double-stranded DNA molecule Parental (template) strand Daughter (new) strand Bubble Replication fork Two daughter DNA molecules (b) Origins of replication in eukaryotes 0.5 µm 0.25 µm Double- stranded DNA molecule

46. Fig. 16-13 Topoisomerase Helicase Primase Single-strand binding proteins RNA primer 5  5  5  3  3  3 

51. Fig. 16-14 A C T G G G G C C C C C A A A T T T New strand 5  end Template strand 3  end 5  end 3  end 3  end 5  end 5  end 3  end Base Sugar Phosphate Nucleoside triphosphate Pyrophosphate DNA polymerase

54. Fig. 16-15a Overview Leading strand Leading strand Lagging strand Lagging strand Origin of replication Primer Overall directions of replication

55. Fig. 16-15b Origin of replication RNA primer “ Sliding clamp” DNA pol III Parental DNA 3  5  5  5  5  5  5  3  3  3 