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Fishing for Chromosomes

Fishing for Chromosomes. Ankur Shah. Chromosome Structure. 23 pairs of chromosomes (22 autosomes) p and q arms; centromere and telomere Normal karyotypes: 46,XX and 46,XY Prophase & metaphase chromosomes consist of 2 identical sister chromatids (held together by the centromere)

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Fishing for Chromosomes

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  1. Fishing for Chromosomes Ankur Shah

  2. Chromosome Structure • 23 pairs of chromosomes (22 autosomes) • p and q arms; centromere and telomere • Normal karyotypes: 46,XX and 46,XY • Prophase & metaphase chromosomes consist of 2 identical sister chromatids(held together by the centromere) • Each germ cell contains only 23 chromosomes (1 member of each pair)

  3. Introduction to Karyotypes • A karyotype is a picture of an organism's genetic make-up in which the chromosomes of a cell have been stained so that the banding pattern of the chromosomes appear. • Cells in Metaphase are stained to show distinct parts of the chromosomes • The cells are then photographed through a microscope and enlarged • The chromosomes are cut from the photograph and arranged according to size, shape, centromere position, and banding patterns.

  4. A Sample Cell during Metaphase

  5. Normal Male Karyotype (46,XY)

  6. Chromosome groups: A - G

  7. Chromosome Abnormalities - Aneuploidy: • N = 23 chromosomes • Euploidy: • Diploid (2n) • Triploid (3n) • Tetraploid (4n) • Aneuploidy • A chromosome number that’s not an exact multiple of n (23 chromosomes) • Due to meiotic non-dysjunction • E.g. Trisomy (T13, 18, 21); Monosomy (Turner syndrome)

  8. Aneuploidy - Trisomy 13

  9. Aneuploidy - Trisomy 18

  10. Triploid Karyotype (69, XXY)

  11. What is FISH? • Fluorescent • In • Situ • Hybridization

  12. Why Use Fish? • Fast • Can utilize Interphase Cells • Translocations • Deletions • Rearrangements • Makes Karyotyping much easier

  13. The Downside of Fishing • Requires large number of cells (200-300) • Expensive! • Can only search for one defect at a time

  14. Examples of Fish

  15. More Examples of Fish

  16. Just a few more

  17. Hey that isnt Fish! THE END

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