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Published byJesse Evans Modified over 9 years ago
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MITOCHONDRIAL GENETICS
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Origin of Mitochondria Endosymbiont Theory Similar size to certain free-living bacteria Similar chromosome & cytoplasm to bacteria Similar ribosomes to bacteria Similar cell division to bacteria Independent replication & gene expression
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Nuclear (Cellular) Chromosomes 3.2 billion total nucleotide pairs MitochondrialChromosomes 2-10 @ per mito 1000-10000 per cell 0.32-1.6 billion total nucleotide pairs total nucleotide pairs
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Genetically Controlled Processes in Mitochondria 13 genes for respiratory chain proteins Subunits of the ATPase complex Subunits for the NADH-dehydrogenase complex 22 genes for tRNAs 2 genes for rRNAs Maintenance of cellular energy levels
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Ataxia v. Ataxia
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Human Mitochondria 2-10 chromos per mito 13 protein-encoding regions 3 subunits of cytochrome c oxidase complex Cytochrome b complex 2 subunits of the ATPase complex 60% occupied by six subunits of NADH dehydrogenase complex 22 tRNAs 2 rRNAs other
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Stability of Mitochondrial DNA Mutatation rate 10X higher than nuclear DNA Mutations generated by oxidation by-products No protective histones Ineffective DNA repair Typically point mutations or deletions Tolerance for deletions variable Some deletions recurring in unrelated patients
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Mitochondrial Diseases General Characteristics Penetrance usually complete (100%) Expressivity highly variable Age of onset variable Frequently limited to specific tissues Usually appear as reduced muscle strength together with degeneration of other tissues Affects organs with high energy requirements: brain, heart, skeletal muscle, eye, ear, liver, pancreas, and kidney
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Some Mitochondrial Diseases Kearns-Sayre syndrome opthalmoplegia, retinal degeneration, cardiomyopathy Lactic-Acidosis-Encephalomyopathy-Stroke syndrome Neurogenic muscle weakness with ataxia and retinitis pigmentosa syndrome Pearson syndrome bone marrow and pancreas failure Diabetes-deafness syndrome
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Maternal Transmittance of Mitochondrial Disease
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heteroplasmy
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Mitochondrial Diseases General Characteristics Penetrance usually complete (100%) Expressivity highly variable Age of onset variable Frequently limited to specific tissues Usually appear as reduced muscle strength together with degeneration of other tissues Affects organs with high energy requirements: brain, heart, skeletal muscle, eye, ear, liver, pancreas, and kidney
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At the course download site: mitogenetics.ppt
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