1. Chapter 12: DNA and RNA Section 12-1: DNA

2. Interest Grabber Section 12-1 1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. 3. Did any of the codes you formed have the same meaning? 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message?

3. Section 1 Answers Interest Grabber Answers 1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats. The units that make up cats are c, a, t, and s. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. Student codes may include: Act; Sat; Cat 3. Did any of the codes you formed have the same meaning? No 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message? Changing the order of the nucleotides changes the meaning of the codon.

4. Order! Order!Order! Order! Genes are made of DNA, a large, complex molecule.Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides.DNA is composed of individual units called nucleotides. Three of these units form a code.Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message.The order, or sequence, of a code and the type of code determine the meaning of the message.

5. Scientists wondered…. What are genes ?What are genes ? What are they made of?What are they made of?

6. Genes… How do they determine the characteristics of critters?How do they determine the characteristics of critters? Can we identify the structure of the “gene” ?Can we identify the structure of the “gene” ? Can we figure out how genes are inherited?Can we figure out how genes are inherited?

7. Genes… Are they single molecules?Are they single molecules? Are they long structures?Are they long structures?

8. A. Griffith and TransformationA. Griffith and Transformation –1. Griffiths Experiment –2. Transformation B. Avery and DNAB. Avery and DNA C. The Hershey Chase ExperimentC. The Hershey Chase Experiment –1. Bacteriophages –2. Radioactive Markers D. The Components and Structure of DNAD. The Components and Structure of DNA –1. Chargaff’s Rules –2. X-Ray Evidence –3. The Double Helix DNA Scientists Video Clip

9. Let’s learn about the scientists involved in DNA research !

10. ScientistContributionConclusion Griffith Avery Hershey-Chase Franklin Wilkins Chargaff Watson-Crick Brenner Gilbert

11. A. Griffith and Transformation 1. Griffiths Experiment 2. Transformation

12. 1. Griffiths Experiment Griffith was looking for something other than a Gene !

13. Frederick Griffith.. In 1928, Griffith wondered how bacteria made people sick.In 1928, Griffith wondered how bacteria made people sick. This is the bacteria that causes pneumonia. Griffith was interested in how this happened.

14. Griffith isolated 2 strains of bacteria that were easily distinguished Disease causing strain had smooth edgesDisease causing strain had smooth edges Harmless strain had rough edges

15. Experiment ExperimentResults Smooth Rough Heat killed smooth Heat killed smooth + harmless rough Construct and Complete

16. How did this happen? Shouldn’t they have lived?

17. Something besides the pneumonia had caused the disease.. But what ?

18. Griffith decided.. Something had caused the heat killed bacteria to pass on their disease causing ability to the harmless bacteriaSomething had caused the heat killed bacteria to pass on their disease causing ability to the harmless bacteria

19. Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia Section 12-1 Figure 12–2 Griffith’s Experiment

20. Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia Section 12-1 Figure 12–2 Griffith’s Experiment

21. Griffith concluded.. The heat killed bacteria had somehow passed on their disease causing ability to the harmless bacteria….The heat killed bacteria had somehow passed on their disease causing ability to the harmless bacteria….

22. 2. Transformation Griffith thought it might be due to a gene !

23. Griffiths last experiment

24. B. Avery Read about Griffiths work and wondered…

25. Avery wondered… What caused the transformation ?What caused the transformation ?

26. So… Avery decided to repeat Griffiths work to determine which molecule had caused the transformation … but with a different approach.Avery decided to repeat Griffiths work to determine which molecule had caused the transformation … but with a different approach.

27. Avery … Decided to destroy each substance in the cells to see which one caused the rough to transform into smooth.Decided to destroy each substance in the cells to see which one caused the rough to transform into smooth.

28. Substance Result in mice ? Transformation factor ? Y/N Polysaccharides Lipids RNA Protein DNA

29. Avery’s Experiment If a substance was destroyed and transformation still occurs, then that substance couldn’t have caused transformation!If a substance was destroyed and transformation still occurs, then that substance couldn’t have caused transformation!

30. Which one caused transformation ?

31. Avery realized… The transforming factor must have been the DNA !The transforming factor must have been the DNA !

32. And that… DNA stores and transmits genetic information from one generation to the next !DNA stores and transmits genetic information from one generation to the next !

33. C. The Hershey Chase Experiment 1. Bacteriophages 2. Radioactive Markers

34. Martha Chase and Alfred Hershey Scientists like Chase and Hershey are skeptics !Scientists like Chase and Hershey are skeptics ! They like to test other peoples work !They like to test other peoples work !

35. 1. Bacteriophages

36. Certain viruses… Attack bacteriaAttack bacteria These are called bacteriophagesThese are called bacteriophages

37. Bacteriophages… They are composed of DNA or RNAThey are composed of DNA or RNA The attach to the surface of a bacteria & inject their DNA/RNAThe attach to the surface of a bacteria & inject their DNA/RNA

38. Here are viruses that attack bacteria

39. HIV is a retrovirus It’s core is RNA, not DNAIt’s core is RNA, not DNA It infects white blood cellsIt infects white blood cells

40. 2. Radioactive Markers Labelling DNA and proteins

41. Hershey & Chase… Wondered which part of the virus infect the cell ?Wondered which part of the virus infect the cell ? Was it the protein or the DNA that caused transformation ?Was it the protein or the DNA that caused transformation ?

42. The did this by…. Labeling the protein with 35 S - a sulfur isotopeLabeling the protein with 35 S - a sulfur isotope And labeling the DNA with 32 P - a phosphorous isotopeAnd labeling the DNA with 32 P - a phosphorous isotope

44. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Figure 12–4 Hershey- Chase Experiment Section 12-1

45. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Section 12-1 Figure 12–4 Hershey- Chase Experiment

46. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Section 12-1 Figure 12–4 Hershey- Chase Experiment

47. Chase & Hershey.. They concluded that the material that caused transformation was DNA!They concluded that the material that caused transformation was DNA!

48. But scientists weren’t yet satisfied ! How could genes carry information to the next generation ?How could genes carry information to the next generation ? How could genes “make” the organism ?How could genes “make” the organism ? How were genes copied ?How were genes copied ?

49. D. The Components and Structure of DNA 1. Chargaff’s Rules 2. X-Ray Evidence 3. The Double Helix

51. DNA is made of nucleotides

52. PurinesPyrimidines Adenine Guanine CytosineThymine Phosphate group Deoxyribose Figure 12–5 DNA Nucleotides Section 12-1 2 rings… 1 ring…

53. Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Figure 12–7 Structure of DNA Section 12-1

54. DNA Bases

55. 1. Chargaff’s Rules Nucleotide pairings…

56. Erin Chargaff… Discovered the percentages of the basesDiscovered the percentages of the bases Notice that…Notice that…

57. Percentage of Bases in Four Organisms Section 12-1 Source of DNAATGC Streptococcus29.831.620.518.0 Yeast31.332.918.717.1 Herring27.827.522.222.6 Human30.929.419.919.8 Streptococcus29.831.620.518.0 Yeast31.332.918.717.1 Herring27.827.522.222.6 Human30.929.419.919.8

58. 2. X-Ray Evidence Franklin & Wilkins

59. Rosalind Franklin Was an expert at X- ray diffraction.Was an expert at X- ray diffraction.

60. X-ray images… Of DNA were created by beaming x-rays at DNA and recording the imagesOf DNA were created by beaming x-rays at DNA and recording the images The X pattern revealed the DNA was a twisted helixThe X pattern revealed the DNA was a twisted helix

61. X-ray images… The angle of the X suggests that there are 2 strandsThe angle of the X suggests that there are 2 strands The shape of the X also revealed that the nitrogen bases were near the center.The shape of the X also revealed that the nitrogen bases were near the center.

62. Maurice Wilkins Maurice also worked on x- ray diffraction but with a different strand of DNAMaurice also worked on x- ray diffraction but with a different strand of DNA

63. 3. The Double Helix The model builders…

64. Watson & Crick Used the data from Franklin’s research to build several models of DNAUsed the data from Franklin’s research to build several models of DNA Their first models were wrong.Their first models were wrong.

65. This is Francis Crick & James Watson Their model explained how DNA could carry information and how it could be copied.Their model explained how DNA could carry information and how it could be copied.

66. The DNA Model

67. DNA Is a double helixIs a double helix The 2 strands wind around each other.The 2 strands wind around each other.

68. Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Figure 12–7 Structure of DNA Section 12-1