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Chromosomal Disorders & Karyotyping

Chromosomal Disorders & Karyotyping. Notes # 5. What causes Chromosomal Disorders?. ANS: Occurs when homologous chromosomes or sister chromatids do not separate, creating unequal # of chromatids in each gamete (sex) cell.

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Chromosomal Disorders & Karyotyping

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  1. Chromosomal Disorders & Karyotyping Notes #5

  2. What causes Chromosomal Disorders? • ANS: Occurs when homologous chromosomes or sister chromatids do not separate, creating unequal # of chromatids in each gamete (sex) cell.

  3. Nondisjunction: The process where chromosomes or chromatids do not split evenly into each daughter cell.

  4. How many chromosomes do healthy individuals have? ANS: There are ________ pairs of body/autosomal chromosomes and _______ pair of sex chromosomes found in each normal body cells. Resulting to a total of ______ pairs homologous chromosomes. 22 1 23

  5. Types of Chromosomal Disorders • Down Syndrome (aka Trisomy 21) • Person has 3 copies of Chromosome #21 • Occurs in 1 of 800 births Chromosome Profile of a Person w/ Down Syndrome

  6. Symptoms of Down Syndrome

  7. 2. Turner’s Syndrome Chromosome Profile of Turner’s Syndrome Occurs in females only She is born with one “X” sex chromosome Her genotype is: XO Health problems: Sterile because sex organs do not develop at puberty.

  8. Turner Syndrome

  9. Chromosome Profile of Klinefelter 3. Klinefelter’s Syndrome Occurs in males Cause: Inheriting extra “X” set chromosomes Genotypes a. XXY b. XXXY c XXXXY Intersex Individuals (used to be called hemaphrodites) Genotype: XXY

  10. How does Klinefelter’s Syndrome Happen? XXY XXY

  11. Klinefelter’s Syndrome

  12. What lab tests are used to detect Chromosomal Disorders before birth? ANS: There are 2 tests, Amniocentesis and Karyotypes. 1. Amniocentesis: A procedure where a needle is inserted into uterus to extract amniotic fluid to obtain fetal cells

  13. 2. Karyotype: Ordered display of chromosomes obtained from fetal cells ordered by size Large (#1) to small (#22) Sex Chr. (#23)

  14. Can you diagnose what chromosomal disorder is displayed by the karyotype seen below? ANS: Klinefelter’s Syndrome (XXY)

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