Biology - Genetics 3

  1. Karyotype
    chromosome composition, the number and appearance of chromosomes in the nucleus.

    • Described short hand by Total#Chromo,SexChromo,Mutations.
    • Ex. Female with Down Syndrom:
    • 47,XX,+21
  2. Down Syndrome
    • trisomy-21, three copies of chromosome 21.
    • 1 in 800 births
    • 47,sex,+21
    • caused by nondisjunction event during meiosis (either parent, mostly female), or during early mitosis (embryogenesis).
    • results in mental issues (too many DYRK proteins) and heart defects
  3. trisomy
    having three copies of one chromosome (2n+1)
  4. triploidy
    having three entire chromosome sets (3x)
  5. XYY & XXX
    • completely harmeless
    • with the extra Y you have so few genes on the Y chromosome
    • with the extra X you simply have two inactivated X chromosomes instead of just 1
  6. Monosomy
    • (2n-1)
    • only viable monosomy in humans is the 45,X, aka Turner Syndrome
  7. Turner Syndrome
    • 45,X
    • female because of lack of Y chromosome. Only viable because normally one X chromosome is inactivated anyways.
    • usually results in shorter than average, infertile, and often heart issues in people. These issues come from the lack of the psudoautosomal region in inactivated X chromosomes
  8. pseudoautosomal region
    genes found on both the X and Y chromosome which escape X chromosome inactivation
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Biology - Genetics 3
Dr. Deyholos Biol 207 Genetics. Final Section. U of A