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Genetic Disorders & Chromosomal Mutations

Genetic Disorders & Chromosomal Mutations. Chapter 12. Karyotype. Karyotype: picture of homologous chromosomes arranged in pairs Human = 46 chromos. = 23 pairs Sex chromosomes = determine sex of human (1 pair) Male: XY Female: XX Autosomes = all others (22 pairs). Pedigree Chart.

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Genetic Disorders & Chromosomal Mutations

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  1. Genetic Disorders & Chromosomal Mutations Chapter 12

  2. Karyotype Karyotype:picture of homologous chromosomes arranged in pairs • Human = 46 chromos. = 23 pairs • Sex chromosomes= determine sex of human (1 pair) • Male: XY • Female: XX • Autosomes = all others (22 pairs)

  3. Pedigree Chart • Shows relationships within a family • Each row is a different generation • Males: ■ Females: ● • Vertical: children; Horizontal: couples • Solid shape: has trait • Used to track appearance of traits • Can infer genotype of family members

  4. Recessive Allele Disorders • Revealed only when dominant allele is absent • Disorders: • 1) PKU (phenylketonuria):newborns lack enzyme to break down phenylaline in milk → severe mental retardation • 2) Tay-Sachs:nervous system breakdown → death by age 4 • Mostly central and eastern Europeans

  5. Tay Sachs PKU

  6. Recessive Allele Disorders • 3) Cystic Fibrosis: Causes respiratory and digestive problems • Most common fatal genetic disorder • 4) Sickle Cell Disease: Results in bent and twisted red blood cells; ↓ blood O2 levels • Causes physical weakness; brain, heart, and spleen damage; death • Closely linked to malaria

  7. Cystic Fibrosis Sickle Cell Disease

  8. Dominant Allele Disorders • Always revealed (even if recessive allele is present) • Disorders: • 1) Acondroplasia:type of dwarfism • 2) Huntington’s disease:progressive loss of muscle and mental functioning • No symptoms until in 30’s

  9. Huntington’s Disease Acondroplasia

  10. Mutations • Mutation: any change in DNA • May involve entire chromosome or single nucleotide • May take place in ANY cell • May be beneficial or deadly (“lethal”) • Occur in 2 types of cells: • Germ-Cell Mutation: occur in gametes (sex cells); passed on to children • Somatic Mutation: occur in body cells

  11. Chromosome Mutations • Non-Disjunction: failure of chromosomes to separate during meiosis • Results in gain/loss of entire chromosome • Trisomy 21: inheritance of extra chromos. #21 • “Down Syndrome”

  12. Karyotype of Trisomy 21

  13. Chromosome Mutations • 1) Deletion: loss of piece of chromosome

  14. Chromosome Mutations • 3) Translocation: swapping segments of non-homologous chromosomes

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