Karyotyping Sex-Linked Traits and Pedigrees! Oh My!

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KaryotypingSex-Linked Traitsand Pedigrees!Oh
My!
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KARYOTYPE

• chart of the chromosomes an individual has.

• SEX CHROMOSOMES X and Y determine the sex
  of an organism.
• XX female
• XY male
• AUTOSOMES 22 pairs of chromosomes
  that do not determine sex.

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Sex Linked Traits

• SEX LINKED TRAIT found on the X chromosome
• AUTOSOMAL TRAIT exists on any chromosome that
  does not determine the sex of the organism.

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Color Blindness

• Sex linked, recessive condition
• Alleles
• Xc color blind
• XC normal vision
• Carrier has a color blind allele but does not
  express the trait (has normal vision).
• XCXc

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Problem Sex linked

• If a woman who is a carrier of the gene for color
  blindness mates with a man with normal vision,
  what offspring will result?

XC Xc
XC Y

• XCXC female normal
• XCXc femal carrier
• XCY male normal
• XcY male color blind

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Pedigrees

• A graphic representation of an individuals
  family tree
• Used to recognize patterns of inheritance

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When are pedigrees used?

• When testcrosses cannot be made
• When number of offspring is too small
• Or if results of testcross would take too long

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Pedigree Symbols

• male unaffected
• male affected
• female unaffected
• female affected
• - marriage
• - offspring