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Allele Important Genetic Concepts Genotype Phenotype Gene
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Mutation (Chapt. 16) Classification of Mutations Mechanisms of Mutagenesis DNA Repair Pathways
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Possible Reading Frames for RNA
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A Comprehensive Catalogue of Somatic Mutations From a Cancer Genome Nature (December 2009) Cancer: Malignant Melanoma Total base substitution mutations: 33,345 Coding mutations: 292 Missense: 172 Nonsense: 15 Silent:105 Total Chromosome mutations: 37
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Old DNA Replication Pg. 279 Template-dependent Semi-conservative 5’ to 3’ Synthesis Old New
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Standard Base Pairs Tautomeric Shift Base Pairs AT G C T G G T AC CA Rare tautomers are shown in Red
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Tautomeric Shift of “A” DNA molecule with TA CG transition mutation Affected base pair Pg. 416
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Oxidation of Guanine 8-oxo-7,8-dihydro-guanine (8-oxoG) ( OH) OHProduced From Electron Transport
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8-oxoG-A Base Pair 8-oxoG Adenine
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Insertion by “Looping Out” of Newly Synthesized Strand
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Deletion by “Looping Out” of Template Strand
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Intercalating Agents Ethidium Bromide
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Ethidium Intercalation in DNA
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Medical Diagnostics X-rays, positrons Radiotherapy X-rays, gamma rays
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Pg. 419
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Pyrimidine Dimer
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(NER) Individuals that are homozygous for loss-of-function alleles of one of the XP genes UV Nucleotide Excision Repair (NER) Pathway (pyrimidine dimer)
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(NER) Damaged DNA Replicated Mutations! UV Nucleotide Excision Repair (NER) Pathway (pyrimidine dimer) Individuals that are homozygous for loss-of-function alleles of one of the XP genes
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Xeroderma pigmentosum
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Sickle Cell Anemia Sickle Cell Trait Normal Red Blood Cells
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Hemoglobin ß-globin (146 amino acids) ß-globin (146 amino acids)
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Molecular Genetics of Sickle-Cell Anemia Hb-A Hb-S Codon #6 Normal Individuals Sickle Cell Individuals E6V
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Hb-S Deoxyhemoglobin
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Polymerized Deoxyhemoglobin (tactoids)
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Molecular Genetics of Sickle-Cell Anemia Hb A Allele Hb S Allele Hb-A Hb-S Codon #6
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Hb-A WT and Mutant ß-globin Proteins Hb Mutant Proteins Hb WT Protein
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Huntington’s Disease
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Mutant Huntingtin Protein Aggregates Transmission Electron Micrograph
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WT Huntingtin-GFPMutant Huntingtin-GFP
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hhHhHH No Htt Protein Aggregates Htt Protein Aggregates No HDHD
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Trinucleotide Repeat Diseases
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Cystic Fibrosis
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CFTR Protein
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Missense mutation Nonsense mutation Frame-shift mutation Deletion, in-frame CFTR Gene Mutations Loss-of-Function Mutations ~1200 pathological mutations Spectrum of Mutations in CFTR Gene
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Frequency of CF Mutant Alleles ~ 70% of CF Mutant alleles are ∆F508
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∆F508 Mutation
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Healthy Lung Lung epithelial cells Lung epithelial cells AA or Aa
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Lung epithelial cells Lung epithelial cells Cystic Fibrosis Lung aa
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Erythropoietin Receptor Mutation And Olympic Glory Seven Olympic medals Eero Mäntyranta
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(Epo)
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Erythropoietin (Epo)
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Red Blood Cell Development
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Genetic Testing Disease-related Diagnosis Current disease Risk of future disease Carrier status Pharmacogenomics Efficacy of therapeutic drug treatment Tissue Typing Transplantation
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Genetic Testing for Sickle Cell Anemia Hb S Hb A Pg. 644 MstII cut sites
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“Prodrug” Tamoxifen Bioactive form of Tamoxifen OH Cytochrome P450 (CYP2D6)
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Cytochrome P450 (CYP2D6) ~ 10% Caucasians are “poor” metabolizers
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Genetic Testing for Tissue Typing Silent Mutations mmmmmmm Missense
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Early Embryonic Development (~ 7 days)
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In Vitro Fertilization (IVF) Sperm cells Embryos (4-cell stage) Oocytes
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Pre-implantation Genetic Diagnosis (PGD) 8-cell Embryo
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Removal viral genes Splice in WT Allele Viral Vector for Gene Therapy WT Allele aaaaa
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Gene Therapy Vectors Retroviruses (e.g. MLV, HIV) Adenoviruses Herpes viruses Cell Host Range Dividing vs. non-dividing cells Overall efficiency of transfer “Evolved” virus
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Hematopoietic Stem Cell Gene Therapy with a Lentiviral Vector in X-Linked Adrenoleukodystrophy Science 6 November 2009: Vol. 326. pp. 818 - 823 Cartier et al (26 authors!)
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X-Linked Adrenoleukodystrophy (ALD) Monogenic Recessive Loss-of-function mutations in ABCD1 gene Defective transport of “very long chain fatty acids” to peroxisomes Multifocal demyelination of CNS cells 1/17,000 newborn boys are affected
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Myelinated Neuron Schwann Cell Myelin
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Hematopoietic Stem Cells (HSCs)
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Brains of ALD Patients Untreated HSC Therapy
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Gene Therapy for Cancer
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Thymidine Kinase Cytosine Deaminase Nitroimidazole reductase GanciclovirPhosphoganciclovir 5-fluorocytosone5-fluorouracil CB1954Alkylating agent EnzymeProdrugToxic Metabolite Gene Therapy for Cancer
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M-Phase Chromosome Interphase (G1, S, G2) Chromosomes
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Giemsa Stain
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Human Euploid Karyotypes FemaleMale Fig. 7-6
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Homologous Chromosomes PM P = Paternal M = Maternal
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2001
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Human Genome Information http://www.ncbi.nlm.nih.gov/ http://www.genome.gov/ http://genomics.energy.gov/
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“Raw” DNA sequence Where are the genes?
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3000 bp scanned for ORFs 5’ 3’ Three Reading Frames Three Reading Frames
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Y58 Mbp397 5 2 13 3 6 4 7 8 9 11 10 14 12 15 16 17 19 20 18 21 X 22 1 ChromosomeDNA sizeORF #ChromosomeDNA SizeORF # 155 Mbp1606 83550 Mbp 47 Mbp425 62 Mbp857 64 Mbp1992 76 Mbp517 79 Mbp1714 89 Mbp1318 100 Mbp1202 106 Mbp1453 3380247 Mbp 243 Mbp2204 1760200 Mbp 191 Mbp1361 181 Mbp1536 1959171 Mbp 159 Mbp1764 1247146 Mbp 140 Mbp1435 1305135 Mbp 134 Mbp2051 132 Mbp1629 649114 Mbp
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X Chromosome 155 Million base pairs (bp) 1606 Genes Muscular Dystrophy Adrenoleukodystrophy Hemophilia A Hemophilia B Green Color Blindness Red Color Blindness X-linked Traits
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Y Chromosome 58 Million base pairs (bp) 344 Genes
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