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Patterns of Chromosome Inheritance

Patterns of Chromosome Inheritance. Chapter 24. Karyotyping. Karyotype Size-ordered chart of the metaphase chromosomes of an individual cell Chromosomal aberration A mutation that is large enough to see under a light microscope. Amniocentesis. Chorionic villi sampling.

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Patterns of Chromosome Inheritance

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  1. Patterns of Chromosome Inheritance Chapter 24

  2. Karyotyping • Karyotype • Size-ordered chart of the metaphase chromosomes of an individualcell • Chromosomal aberration • A mutation that is large enough to see under a light microscope

  3. Amniocentesis

  4. Chorionic villi sampling

  5. Normal male karyotype

  6. Down syndrome karyotype

  7. Changes in Chromosome Number • Nondisjunction • Result after fertilization: • Trisomy • Monosomy

  8. Nondisjunction in Meiosis I

  9. Nondisjunction in Meiosis II

  10. Down Syndrome

  11. Changes in Sex Chromosome Number • Y chromosome-determines maleness. • SRY gene produces a testis-determining factor • Caused by non-disjunction

  12. Non-disjunction in Sex Chromosomes Y chromosome-determines maleness. Results of non-disjunction?: XXX XXY XYY X0 0Y Survivable with problems Survivable with problems Survivable with problems Survivable with problems Lethal

  13. Non-disjunction in Sex Chromosomes • Turner Syndrome --XO • Klinefelter Syndrome—XXY • Poly-X Females---XXX • Jacobs Syndrome---XYY

  14. Changes in Chromosome Structure • Mutation– a permanent genetic change. • Chromosome mutation--change in chromosome structure. • Types: • Inversion • Translocation • Deletion • Duplication

  15. Deletion

  16. Duplication

  17. Translocation

  18. Inversion

  19. WHAT’S HAPPENING??

  20. Sex-Linked Traits • Traits controlled by genes on the X or Y chromosomes are sex-linked although most are unrelated to gender. • An allele on the X chromosome that is in the region where the Y chromosome has no alleles will express even if recessive; it is termed X-linked. • A female would have to have two recessive genes to express the trait; a male would only need one.

  21. X-Linked Alleles • The key for an X-linked problem shows the allele attached to the X as in: • XB = normal vision • Xb = color blindness. • Females with the genotype XBXb are carriers because they appear to be normal but each son has a 50% chance of being color blind depending on which allele the son receives. • XbXb and XbY are both colorblind.

  22. Cross involving an X-linked allele

  23. X-linked recessive pedigree chart

  24. X-Linked Disorders • Red-green color blindness • Muscular dystrophy. • Hemophilia.

  25. http://perth.uwlax.edu/faculty/howard/BIO101/DNA&translation/sld002.htmhttp://perth.uwlax.edu/faculty/howard/BIO101/DNA&translation/sld002.htm

  26. Diana http://brie.medlabscience.med.ualberta.ca/de/genetics/70gen-hemophil.html

  27. Chapter Summary • Humans - 22 pairs of autosomes and one pair of sex chromosomes • Abnormalities of chromosome number or composition. • Males - XY • Females -XX. • Chromosomal mutations • Sex-linked traits

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