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Genetics: Karyotypes

Learn about genetics, karyotypes, and chromosomal traits passed down from parents. Explore sex chromosomes, abnormalities like Down's syndrome, and more.

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Genetics: Karyotypes

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  1. Genetics: Karyotypes

  2. Chromososmes • Traits are passed on to you from your parents through chromosomes. • Half of your chromosomes come from your father and half from your mother.

  3. Karyotype – An ordered arrangement of a person’s chromosomes

  4. Sex Chromosomes vs. Autosomes • Sex Chromosomes (23rd pair)– The X and Y chromosomes which determine a person’s sex • Which sex is XY? Male • Which sex is XX? Female • Autosomes – Paired chromosomes 1-22, same in both sexes

  5. How Karyotypes are Made • Cells of a person or fetus are photographed during mitosis when the chromosomes are condensed and easy to see - Prophase

  6. How Karyotypes are Made • The photograph is then cut and the chromosomes are arranged in order of size

  7. Amniocentesis – taking the fluid from around a fetus to make a karyotype

  8. Normal Human Karyotype • 23 pairs of Chromsomes • 1-22 - Autosomes • 23 - sex chromosomes

  9. Karyotype Abnormalities • Monosomy- having one chromosome rather than a pair • Trisomy – having three chromosomes rather than a pair • Both occur because of nondisjunction during meiosis

  10. Nondisjuction – when a doubled chromosome doesn’t split during meiosis • These 4 cells will each become eggs or sperm, two of which will have abnormal numbers of chromosomes. Which two?

  11. Trisomy 21 = Down’s Syndrome

  12. Down Syndrome • Happens 1 in 700 births • Individuals have broad, flat faces, mild to moderate mental retardation, and sometimes respiratory problems • Usually live slightly shortened life-spans

  13. Trisomy 18 = Edward’s Syndrome

  14. Edward’s Syndrome • Happens 1 in 10,000 births • Individuals have malformed ears and hands, mental retardation, and heart disease • Most don’t live past a few years

  15. 47, XXY = Kleinfelter’s Syndrome

  16. Kleinfelter’s Syndrome • Happens 1 in 1000 male births • Individuals are sterile, have some feminine characteristics such as breast enlargement and little facial hair, normal intelligence

  17. Monosomy X = Turner’s Syndrome

  18. Turner’s Syndrome • Happens 1 in 5000 female births • Individuals do not develop sexually during puberty and are sterile, but have normal intelligence • The only monosomy that is survivable in humans!

  19. What can you tell about this person from their karyotype?

  20. Now, get out a piece of paper for the Karyotype Lab • Do not write on the paper • Following the instructions

  21. 1. Billy 2. Will • 3. Tommy (left) • 4. Suzy 5. Jen

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