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Published byHugh Moody Modified over 9 years ago
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The chemical Basis of Inheritance
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Chromatin / Chromosomes
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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 23000 bases 12 Caenorhabditis elegans 97 million bases 19,100 1 gene per 5000 bases 6 (roundworm) Saccharomyces cerevisiae 12 million bases 6300 1 gene per 2000 bases 16 (yeast) Escherichia coli 4.7 million bases 3200 1 gene per 1400 bases 1 (bacteria) H. influenzae (bacteria) 1.8 million bases 1700 1 gene per 1000 bases 1
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Chromosome = Protein + DNA
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Indirect Evidence of DNA as genetic material
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Bacteria transforming factor- Griffiths 1928
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Hershey and Chase Expt. 1952 Viral Life Cycle I
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Viral Life cycle II attachment, penetration, replication, assembly, lysis
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Hershey and Chase – Protein coat labeled virus
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Hershey and Chase – DNA labeled virus
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32P - Radioactivity appear in progeny
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35S – No Radioactivity in progeny
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Hershey and Chase
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Watson and Click Model 1953
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DNA – A Double Helix
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DNA – Sugar phosphate backbone
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DNA – Polynucleotide chain
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DNA – A Nucleotide unit
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DNA – Sugar / pentose
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DNA – Organic Bases Purines Pyrimidine
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DNA – Base pairing
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DNA – 2 antiparallel chains
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DNA vs RNA
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DNA - The molecule of life Each cell: 46 chromosomes 2 meters of DNA 3 billion DNA bases Approximately 30,000 genes
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From DNA to Human
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DNA replication – overall process
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DNA replication
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Three models of DNA replication
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Evidence for a Semi-conservative model
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Semi-conservative replication
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DNA replication
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The triplet code I
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The triplet code II- start
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The triplet code III- termination
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The triplet code IV- degenerate
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The triplet code IV- Non-overlapping
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The triplet code V – no punctuation
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Breaking the code
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Central Dogma
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Transcription
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Transcription- animated
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Transcription- coding strand
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Replication - transcription - translation
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t-RNA
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t-RNA binding sites
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Aminoacyl-tRNA complex
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Ribosome – Pro- and Eukaryotic
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Ribosome- P and A sites
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Translation
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Translation- animated
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Gene regulation _Operon 1
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Gene regulation _Operon 2
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Gene regulation _Operon 3
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Mutation
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Mutation_altered genetic info
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Types of mutation
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Causes of mutation Spontaneous Chemical mutagens Physical agents
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Results of mutation Extra compound eyes Variations in pigments Both Wings on same side Sickled cell anaemia
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Somatic vs Germinal mutation
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Early vs Late somatic mutation
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Karyotype
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To obtain a karyotype
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Down syndrome_aneuploidy
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Down syndrome
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Eye-folds
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Frequency of Down’s syndrome against mother’s age
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Kleinfelter syndrome
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Chromosome Mutation-non disjunction I
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Chromosome Mutation-non disjunction II
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XYY
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XY vs XYY
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XO
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XO _Turner syndrome
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Euploidy_Autopolyploidy
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Autopolyploidy_seedless fruit
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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.
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Hybrid_sterililty
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Unpaired chromosomes—results in abnormal gamtes
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Doubling of chromosomes allowing pairing of chromosomes and production of normal gametes
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Allopolyploidy_principle
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Allopolyploidy in cabbage
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Allopolyploidy_Wheat
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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
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Significance of mutation
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