1. DNA Structure and Function
Homework #1 is posted and due 9/20
Bonus #1 is posted and due 10/25

2. How is information transferred between cells?
Fig 7.2
Different strains of bacteria are injected into mice.

3. How is information transferred between cells?
Fig 7.2

4. How is information transferred between cells?
Fig 7.2

5. How is information transferred between cells?
Fig 7.2

6. What has happened to the bacteria?
Fig 7.2
What has happened to the bacteria?

7. DNA is the transforming agent
Fig 7.3

8. If these two can win a Nobel prize…
The Structure of DNA
If these two can win a Nobel prize…
James Watson and
Francis Crick

9. Data showing uniformity of DNA structure.
Rosalind Franklin

10. Nucleotides have a sugar backbone
Fig
Nucleotides have a sugar backbone

11. This subtle difference in structure has profound effects.
Fig
This subtle difference in structure has profound effects.

12. Plus four different bases
Fig
Plus four different bases

13. Together with a phosphate = nucleotide
Fig 7.5

14. Together with a phosphate = nucleotide
Fig 7.5
Together with a phosphate = nucleotide

15. Connect nucleotides by covalent bond = strand
Fig 7.8
Connect nucleotides by covalent bond = strand

16. DNA is typically double stranded
Fig 7.8
DNA is typically double stranded
The strands are connected by hydrogen bonds

17. Data showing uniformity of DNA structure.
Rosalind Franklin

18. Fig 7.8
Base pairing in DNA
Figure 7-10

19. Fig 7.9
Two representations of the DNA double helix
Figure 7-9

20. Fig 8.11
DNA stores information, but does not do anything. The information must be expressed to be useful.

21. The relationship between DNA and genes
a gene
promoter
coding region
terminator
non-gene
DNA

22. DNA Composition: In humans:
Each cell contains ~6 billion base pairs of DNA.
This DNA is ~2 meters long and 2 nm wide.
~97% does not directly code for amino acids
In a single human cell only about 3-5% of genes are expressed at a time.

23. Length of
human DNA
in each cell
Width of DNA

24. DNA Composition: In humans:
Each cell contains ~6 billion base pairs of DNA.
This DNA is ~2 meters long and 2 nm wide.
~3% directly codes for amino acids
~10% is genes
In a single human cell only about 5-10% of genes are expressed at a time.

25. The relationship between DNA and genes
a gene - DNA used to produce RNA or protein
promoter
coding region
terminator
non-gene
DNA

26. Five Perspectives of a Gene

27. Genes act as units of heredity…storing and passing on information.

28. Genes act as units of heredity…
storing and passing on information.

29. Genes are seen as a cause of disease

30. Genes are seen as a cause of disease

31. Sickle-cell anemia is caused by a single nucleotide change in the hemoglobin gene
Fig 6.5

32. Genes code for proteins
Fig 8.11
Genes code for proteins

33. Proteins are the “doers” of the cell. They act as: Enzymes
Genes code for proteins…
Proteins are the “doers” of the cell.
They act as:
Enzymes
Structural Support
Transporters
Signals

34. Genes act as switches, controlling development

35. Genes act as switches, controlling development

36. Genes are replicators (selfish gene)
From “Biology 7th ed.” by Campbell et al fig 19.14

37. Viruses infect living cells, take over, and produce more virus.
Fig 5.25
Viruses infect living cells, take over, and produce more virus.

38. Bodies are vessels for the transmission of genes

39. Five Perspectives of Genes:
Genes act as units of heredity
Genes are seen as a cause of disease
Genes code for proteins
Genes act as switches, controlling development
Genes are replicators (selfish gene)

40. Transposons

41. Transposons: mobile DNA
Genes are replicators (selfish gene)
Transposons: mobile DNA

42. Barbara McClintock, discoverer of transposons

43. Transposons are self-moving DNA
Fig 14.8

44. Transposons move within genomes via the action of transposase
Fig 14.8
Transposons move within genomes via the action of transposase

45. Fig 14.4
transposase
transposon

46. Fig 14.4

47. Fig 14.4

48. Fig 14.4

49. Fig 14.4

50. Genes are replicators (selfish gene)
From “Biology 7th ed.” by Campbell et al fig 19.14

51. Transposons: mobile DNA
Genes are replicators (selfish gene)
Transposons: mobile DNA

52. Five Perceptions of Genes:
Genes act as units of heredity
Genes are seen as a cause of disease
Genes code for proteins
Genes act as switches, controlling development
Genes are replicators (selfish gene)

53. We did NOT cover this in class
We did NOT cover this in class. I left it in if you are interested in learning more about it. This article in Nature has some good info:
The RNA World pg 312

54. This subtle difference in structure has profound effects.
Fig
This subtle difference in structure has profound effects.

55. Connect nucleotides by covalent bond = strand (notice 5’-3’ bond)
Fig 7.8
Connect nucleotides by covalent bond = strand
(notice 5’-3’ bond)

56. Fig 8.11
DNA stores information, but does not do anything. The information must be expressed to be useful.

57. Where did this system come from?
Fig 8.11
Where did this system come from?

58. Was RNA the first biological molecule?
The RNA World pg 312

59. Living organisms must fit all of the following criteria: (modified from Campbell “Biology”)
1. They must have organization.
2. They must have metabolism.
3. They must respond to the environment.
4. They must be able to reproduce themselves.

60. Fig 8.2 U*
RNA structure A G C

61. RNA can form base pairs within single stranded molecule
Fig

62. RNA can form complex 3-D structures
Ribosomes (rRNA) have enzymatic activity:
Enzymatic RNA=ribozyme
Fig 9.12

63. Some RNA molecules have catalytic activities
pg 223

64. Living organisms must fit all of the following criteria: (modified from Campbell “Biology”)
1. They must have organization.
2. They must have metabolism.
3. They must respond to the environment.
4. They must be able to reproduce themselves.

65. RNA can (theoretically) be replicated using complementary bases

66. Experimental determination of RNA’s ability to
self-ligate…
A step towards self-replication
from Freeman’s “Biological Science” (2002) chapter 3

67. Q: Can RNA self-ligate? Hypos: Yes. No.
from Freeman’s “Biological Science” (2002) chapter 3

69. Column Chromatography
RNA’s added in aqueous solution
Some, with tag, bind to column
Without tag, flow thru

71. Overall RNA self-ligation improves by selection

72. Theoretical evolution of self-replicating RNA

73. Hypothetical Origin of Life
pg 214