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How could we get a genetic disorder?
Agenda for Wednesday Jan 11th Epistasis/polygenic Genetic Disorders Posters
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Karyotype the number and appearance of chromosomes
length, the position of centromeres, banding pattern, differences between the sex chromosomes, and other physical characteristics
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Nondisjunction Occurs when chromosomes fail to separate during anaphase I or anaphase II More chromosomes than usual Trisomy – set of three chromosomes of one kind Monosomy – set of 1 chromosome
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Nondisjunctions Down Syndrome (trisomy 21)
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Other Nondisjunctions
Patau syndrome (trisomy 13): serious eye, brain, circulatory defects as well as cleft palate. Children rarely live more than a few months Edward's syndrome (trisomy 18): almost every organ system affected Children with full Trisomy 18 generally do not live more than a few months
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Nondisjunction of the sex chromosomes (X or Y chromosome)
Klinefelter syndrome: 47, XXY males. Male sex organs unusually small testes, sterile Breast enlargement and other feminine body characteristics Normal intelligence
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47, XYY males Trisomy X: 47, XXX females
Individuals are somewhat taller than average often have below normal intelligence At one time (~1970s), it was thought that these men were likely to be criminally aggressive, but this has been disproven over time Trisomy X: 47, XXX females healthy and fertile - usually cannot be distinguished from normal female except by karyotype
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Monosomy X (Turner's syndrome)
the only viable monosomy in humans - women with Turner's have only 45 chromosomes!!! XO individuals are genetically female do not mature sexually during puberty and are sterile Short stature and normal intelligence 98% of these fetuses die before birth
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Posters
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Pedigrees Pedigree – diagram that traces the inheritance of a particular trait through several generations
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Pedigrees Symbols
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Analyzing Pedigrees
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Inferring Genotypes Use pedigrees to infer genotypes
Determine genotype from phenotype Dominant traits are easier to identify dominant traits are exhibited in the phenotype If good records have been kept you can predict disorders in future offspring
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What is a pedigree? Agenda for Tuesday May 3rd Pedigrees DNA
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Polydactyl – Dominant Disorder
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Questions Is this trait dominant or recessive? Explain your answer.
Name the 2 individuals that were carriers of hemophilia How are individuals III-1 and III-2 related? How many children did individuals I-1 and I-2 have How many girls did II-1 and II-2 have? How many have hemophilia?
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Is this a recessive or dominant trait
Is this a recessive or dominant trait? How are person II2 and II3 related? Agenda Pedigree Review Pedigree Practice Movie
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The pedigree to the right shows a family’s pedigree for colorblindness (a sex linked trait)
Which sex can be carriers of colorblindness and not have it? Why does individual IV-7 have colorblindness? Why do all the daughters in generation II carry the colorblind gene? IV
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