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The chemical Basis of Inheritance. Chromatin / Chromosomes.

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Presentation on theme: "The chemical Basis of Inheritance. Chromatin / Chromosomes."— Presentation transcript:

1 The chemical Basis of Inheritance

2 Chromatin / Chromosomes

3 Organism estimated size estimated gene number average gene density chromosome # Homo sapiens (human) 2900 million bases ~30,000 1 gene per 100,000 bases 46 Rattus norvegicus (rat) 2,750 million bases ~30,000 1 gene per 100,000 bases 42 Mus musculus (mouse) 2500 million bases ~30,000 1 gene per 100,000 bases 40 Drosophila melanogaster 180 million bases 13,600 1 gene per 9,000 bases 8 (fruit fly) Arabidopsis thaliana 125 million bases 25,500 1 gene per 4000 bases 5 (plant) Zea mays (corn) 5000 million bases ~25,000 1 gene per 200,000 bases 10 Oryza sativa (rice) 565 ~25,000 1 gene per bases 12 Caenorhabditis elegans 97 million bases 19,100 1 gene per 5000 bases 6 (roundworm) Saccharomyces cerevisiae 12 million bases gene per 2000 bases 16 (yeast) Escherichia coli 4.7 million bases gene per 1400 bases 1 (bacteria) H. influenzae (bacteria) 1.8 million bases gene per 1000 bases 1

4 Chromosome = Protein + DNA

5 Indirect Evidence of DNA as genetic material

6 Bacteria transforming factor- Griffiths 1928

7 Hershey and Chase Expt Viral Life Cycle I

8 Viral Life cycle II attachment, penetration, replication, assembly, lysis

9 Hershey and Chase – Protein coat labeled virus

10 Hershey and Chase – DNA labeled virus

11 32P - Radioactivity appear in progeny

12 35S – No Radioactivity in progeny

13 Hershey and Chase

14 Watson and Click Model 1953

15 DNA – A Double Helix

16 DNA – Sugar phosphate backbone

17 DNA – Polynucleotide chain

18 DNA – A Nucleotide unit

19 DNA – Sugar / pentose

20 DNA – Organic Bases Purines Pyrimidine

21 DNA – Base pairing

22

23 DNA – 2 antiparallel chains

24 DNA vs RNA

25

26 DNA - The molecule of life Each cell: 46 chromosomes 2 meters of DNA 3 billion DNA bases Approximately 30,000 genes

27 From DNA to Human

28 DNA replication – overall process

29 DNA replication

30 Three models of DNA replication

31 Evidence for a Semi-conservative model

32 Semi-conservative replication

33 DNA replication

34 The triplet code I

35 The triplet code II- start

36 The triplet code III- termination

37 The triplet code IV- degenerate

38 The triplet code IV- Non-overlapping

39 The triplet code V – no punctuation

40 Breaking the code

41

42 Central Dogma

43 Transcription

44 Transcription- animated

45 Transcription- coding strand

46 Replication - transcription - translation

47 t-RNA

48 t-RNA binding sites

49 Aminoacyl-tRNA complex

50 Ribosome – Pro- and Eukaryotic

51 Ribosome- P and A sites

52

53 Translation

54 Translation- animated

55 Gene regulation _Operon 1

56 Gene regulation _Operon 2

57 Gene regulation _Operon 3

58 Mutation

59

60 Mutation_altered genetic info

61 Types of mutation

62 Causes of mutation Spontaneous Chemical mutagens Physical agents

63 Results of mutation Extra compound eyes Variations in pigments Both Wings on same side Sickled cell anaemia

64 Somatic vs Germinal mutation

65 Early vs Late somatic mutation

66 Karyotype

67 To obtain a karyotype

68 Down syndrome_aneuploidy

69 Down syndrome

70 Eye-folds

71 Frequency of Down’s syndrome against mother’s age

72 Kleinfelter syndrome

73

74 Chromosome Mutation-non disjunction I

75 Chromosome Mutation-non disjunction II

76 XYY

77 XY vs XYY

78 XO

79 XO _Turner syndrome

80 Euploidy_Autopolyploidy

81 Autopolyploidy_seedless fruit

82 How to make seedless fruits? The resulting 3n zygote develops into a 3n embryo inside a seed. Planting this seed will yield a 3n watermelon plant bearing 3n seedless watermelons.

83 Hybrid_sterililty

84 Unpaired chromosomes—results in abnormal gamtes

85 Doubling of chromosomes allowing pairing of chromosomes and production of normal gametes

86 Allopolyploidy_principle

87 Allopolyploidy in cabbage

88

89 Allopolyploidy_Wheat

90 Gene-mutation_Sickled cell anaemia The amino acid sequences for the normal and abnormal P chains differ in the substitution of valine for glutamic acid at one point in the abnormal polypeptide chains of haemoglobin S

91 Significance of mutation


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