[17.5-6] codominance, multiple alleles, and sex-linkage Flashcards
1
Q
describe the shorthand for codominant alleles (good luck)
A
- put them as superscripts on a letter that represents that gene eg. CᴿCᵂ
- cross these in normal 2x2 punnett square
2
Q
describe the possible genotypes for each blood type
A
- A = IᴬIᴬ or IᴬIᴼ
- B = IᴮIᴮ or IᴮIᴼ
- AB = IᴬIᴮ
- O = IᴼIᴼ
3
Q
what happens when there are multiple alleles?
A
- only 2 can be present in an individual at any one time
- some alleles are codominant and some are recessive to both
4
Q
who can fathers pass sex-linked alleles on to?
A
daughters but not sons
5
Q
who can mothers pass sex-linked alleles on to?
A
both sons and daughters
6
Q
describe the differences between how sex-linked recessive traits are expressed
A
- in females, these traits will be expressed only in the homozygous condition
- any male receiving the recessive allele from his mother will express the trait
- feamles can be carriers for recessive alleles but males cannot
7
Q
what are some examples of sex-linked conditions?
A
- colour blindness
- duchenne muscular dystrophy
- haemophilia
- hunter syndrome
- menkes disease
8
Q
why does sex-linkage occur?
A
- female = XX, male = XY
- no homologous portion on Y chromosome that might have dominant allele
9
Q
describe the nomenclature for sex-linked punnet squares
A
XᴬXᵃ, XᵃY⁻
10
Q
pedigree charts
A
- male = square
- female = circle
- shading = presence of characteristic
