1. Ch. 9 Notes DNA: The Genetic Material
By: Brianna Shields
December 8, 2005

2. DO NOW 1. Which scientist(s) “discovered” transformation?
2. Hershey and Chase verified the finding that what material is transferred during transformation?
3. What type of lab organism did Hershey and Chase use in their experiments?

3. Complementary Base Pair DNA Replication DNA Helicase Replication Fork
List the terms in your vocab notebook, leaving about 3-4 spaces between each term
Vaccine
Virulent
Transformation
Bacteriophage
Double Helix
Nucleotide
Deoxyribose
Base-pairing Rules
Complementary Base Pair
DNA Replication
DNA Helicase
Replication Fork
DNA Polymerase

4. GOALS
Relate Griffith’s conclusions to the observations he made during the transformation experiments
Summarize the steps involved in Avery’s transformation experimentsand state the results
Evaluate the results of the Hershey and Chase experiment
Describe the three components of a nucleotide
Develop a model of the structure of a DNA molecule
Evaluate the contributions of Chargaff, Franklin and Wilkins in helping Watson and Crick determine the double helical structure of DNA
Relate the role of the base pairing rules to the structure of DNA
Summarize the process of DNA replication
Describe how errors are connected during DNA replication
Compare the number of replication forks in prokaryotic and eukaryotic DNA

5. DNA: The Genetic Material
Griffith’s Experiment
Trying to develop a vaccine (killed/weakened bacteria or virus introduced to body to protect from future infection)

6. DNA: The Genetic Material
Griffith’s Experiment
Two strains of streptococcus pneumoniae
S - virulent (disease causing), has capsule, grows in smooth colonies
R- non disease causing, no capsule, grows in rough colonies

8. DNA: The Genetic Material
Griffith’s Experiment
1. Mice injected with S died
2. Mice injected with R were healthy

9. DNA: The Genetic Material
Griffith’s Experiment
3. Was bacterial capsule causing death in mice?

10. DNA: The Genetic Material
Griffith’s Experiment
4. Inject mice with dead S bacteria- mice remained healthy

11. DNA: The Genetic Material
Griffith’s Experiment
5. Injected mice with heat killed S bacteria- (can’t reproduce but still have capsule)- mice lived

12. DNA: The Genetic Material
Griffith’s Experiment
6. Injected mixed harmless live R with heat killed S into mice- mice died

13. DNA: The Genetic Material
Griffith’s Experiment
7. Mouse blood contained R bacteria that had acquired capsules (somehow changed and became virulent S bacteria)
Discovered TRANSFORMATION

15. Griffith's
Experiment

16. DNA: The Genetic Material
Transformation
Change in genotype caused when cells take in foreign genetic material

17. DNA: The Genetic Material
Avery’s Experiment
What substance is responsible for transformation?
Added protein destroying enzymes to heat killed S and healthy R mixture- transformation occurred
Added DNA destroying enzymes to same mixture- transformation stopped

19. DNA: The Genetic Material
Hershey and Chase Experiment
Wanted to confirm that DNA (not proteins) carried genetic material

20. DNA: The Genetic Material
Hershey and Chase Experiment
Known facts
A. Viruses made of DNA or RNA surrounded by protective protein coat

21. DNA: The Genetic Material
Hershey and Chase Experiment
Known facts
B. Bacteriophages (viruses) infecxt bacteria to produce more viruses (released when bacteria host ruptures)

22. DNA: The Genetic Material
Hershey and Chase Experiment
Known facts
C. Only DNA in phage contained phosphorus
D. Only protein coat in phage contained sulfur

23. DNA: The Genetic Material
Hershey and Chase Experiment
1. Grew a sample of T2 bacteriophage in radioactive sulfur medium (would be used in T2’s protein coat)

24. DNA: The Genetic Material
Hershey and Chase Experiment
2. Grew a sample of T2 bacteriophage in radioactive phosphorus medium (would be used in T2’s DNA)

25. DNA: The Genetic Material
Hershey and Chase Experiment
3. Allowed S and P labeled phages to infect E. coli bacteria
Can detect radioactive S and P to see if DNA, protein or both are transferred to E. coli

26. DNA: The Genetic Material
Hershey and Chase Experiment
4. S and P phages removed from bacteria using blender
5. Centifuge spins heavy bacteria to bottom and light phages to liquidy top of mixture

27. DNA: The Genetic Material
Hershey and Chase Experiment
6. Findings:
A. S label found only in phages (protein never injected into E. coli)
B. P label found mostly in bacteria (DNA transferred to E. coli)
C. New generation of phages from bursted bacteria also contained radioactive DNA

30. DNA: The Genetic Material
Hershey and Chase Experiment
7. Conclusion:
DNA is transferred from virus to bacteria
Protein remains outside cell
DNA must be hereditary material (atleast in viruses)

31. Assessment One Summarize Griffith’s transformation experiments
Describe how Avery’s experiment supplied evidence that DNA, not protein is the genetic material
Describe the contributions of Hershey and Chase to the understanding that DNA is the genetic material
Why did heat kill Griffith’s S bacteria?
What might Hershey and Chase have concluded if they had found P and S in the bacteria cells?

32. DNA: The Genetic Material
Watson and Crick
Established the structure of DNA
Made a tin and wire model of DNA

33. DNA: The Genetic Material
Structure of DNA
1. Double helix- 2 strands of linked nucleotides twisted around like a winding staircase

34. DNA: The Genetic Material
Structure of DNA
2. Nucleotides- subunits that make up DNA, composed of:
Phosphate group
Five carbon sugar molecule (deoxyribose)
Nitrogen containing base (four kinds)
Adenine
Guanine
Thymine
Cytosine
Bases pair up to create” ladder rungs”

37. DNA: The Genetic Material
Structure of DNA
3. Base classification
Purines- double ring of C and N atoms
Adenine and Guanine
Pyrimidines- single ring of C and N atoms
Thymine and Cytosine

38. DNA: The Genetic Material
Structure of DNA
4. Helix held together by weak hydrogen bonds between paired bases

39. DNA: The Genetic Material
Chargaff
Discovered base pairing rule
Amounts of adenine and thymine in DNA are always the same
Amounts of cytosine and guanine in DNA are always the same
Amounts of A and T, and G and C differ

41. DNA: The Genetic Material
Wilkins and Franklins Photographs
Bounced X rays off DNA to create pattern scattered onto film
Photos indicate DNA is a tightly coiled helix with 2 chains of nucleotides

42. DNA: The Genetic Material
Pairing between bases
Because of size and structure of bases, only certain ones pair up to hold DNA together
Adenine - Thymine
Guanine - Cytosine

45. DNA: The Genetic Material
Pairing between bases
Results in complementary base pairs
Sequence on one strand of DNA can determine sequence of other strand

47. Assessment Two Describe the three parts of a DNA molecule
Relate the base pairing rules to the structure of the DNA
Describe the two pieces of information from other scientists that enabled Watsons and Crick to discover the double helical structure of DNA
Explain why the two strands of the double helix are described as complementary
What would be the complementary strand to DNA with the following base sequence: AGCTTAGTCA

48. DNA: The Genetic Material
Replication of DNA
Making a copy of DNA
Complementary strands of DNA serve as template for replicating DNA
Occurs during S phase of cell cycle (before division)

50. DNA: The Genetic Material
Replication of DNA
Steps:
A. DNA helicase unwinds and opens DNA by breaking H bonds between bases

51. DNA: The Genetic Material
Replication of DNA
Steps:
B. Helix separates at replication forks (Y shape), proteins attach to DNA and hold helix open

52. DNA: The Genetic Material
Replication of DNA
Steps:
C. DNA polymerase enters fork, moves along DNA strand adding nucleotides to exposed bases according to pairing rule
Proofreads, removes and fixes any mismatched nucleotides
Reduces error to 1 in a billion

54. DNA: The Genetic Material
Replication of DNA
Steps:
D. DNA polymerase continues until DNA is copied, then it is signaled to detach

56. DNA: The Genetic Material
Replication of DNA
Result: 2 new DNA double helices created (identical to each other and original DNA)

58. DNA: The Genetic Material
Rate of DNA replication
In circular prokaryotic DNA
2 replication forks that move away from one another until they meet on other side of DNA circle

59. DNA: The Genetic Material
Rate of DNA replication
In eukaryotic DNA
End o end replication would take a month for one strand of DNA
Have multiple replication forks so several DNA portions are replicated simultaneously
One human chromosome takes 8 hours

60. Assessment Three
Explain the two roles that enzymes play in DNA replication
Explain the relationship between DNA polymerases and mutation
State the effect of multiple replication forks on the speed of replication in eukaryotes
If a mutation occurs during the formation of an egg cell or sperm cell, is that mutation more significant or less significant than a mutation that occurs in a body cell?

61. Websites Gene Scene DNA Workshop The Geee! In Genome
Putting DNA to work
Kids Genetics: DNA
Hershey and Chase Experiment Animation
DNA Replication Animation
Another DNA Replication Animation