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)
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
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