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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 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.
Nondisjunction: The process where chromosomes or chromatids do not split evenly into each daughter cell.
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
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
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.
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
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
2. Karyotype: Ordered display of chromosomes obtained from fetal cells ordered by size Large (#1) to small (#22) Sex Chr. (#23)
Can you diagnose what chromosomal disorder is displayed by the karyotype seen below? ANS: Klinefelter’s Syndrome (XXY)