Genetics 3 Flashcards

1
Q

How do we label genes and their alleles for for sex-linked traits?

A

Recall:
Male = XY
Female = XX

Sex-linked genes:

FEMALES: MALES:

X^A X^A X^A Y (homozygous Dominant)
X^A X^a X^a Y ( homozygous Recessive)
X^a X^a N/A. (Heterozygous)

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2
Q

X-linked rescessive: (sex-linked)

A
  • Males often have the disease
  • females are carriers (Carries the bad gene but does not express it). Because:
    a) their father has the gene and the mother is not a carrier.
    b) their mother is a carrier and father is unaffected
  • every affected son Has a carrier mother and healthy father
  • trait often skips a generation
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3
Q

X-linked dominant:

A
  • both males and females re equally affected
  • if father is affected, all daughters are affected but no sons
  • if mother is affected about half her children will be affected (both son and daughter)
  • the trait does not skip a generation
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