Ch 4.1 Incomplete Dominance, Codominance, Overdominance, Sex-linked student

Types of Inheritance Patterns
- Incomplete Dominance: A form of dominance where the heterozygote phenotype is intermediate between the two homozygous phenotypes.
- Codominance: Both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits.
- Overdominance: The heterozygote has a greater fitness than either homozygote.
- Sex-linked Traits: Traits associated with genes located on the sex chromosomes.
- Sex-influenced Traits: Traits whose expression is influenced by the sex of the individual.
- Sex-limited Traits: Traits that only manifest in one sex, despite both sexes carrying the alleles.

Genotypes and Phenotypes: Color determined by three alleles (R1, R2, r) where red (R1) > purple (R2) > green (r).
- Crosses and Expected Ratios:
  - a. R1/R2 X R1/r:
    - Genotype ratios: 3 R1:1 R2:1 r
    - Phenotype ratios: 2 red:1 purple:1 green
  - b. R1/r X R2/r:
    - Genotype ratios: 1 R1/R2:1 R1/r:1 R2/r:1 r/r
    - Phenotype ratios: 2 red:1 purple:1 green

Genotypes and Phenotypes:
- Yellow body color (X-linked recessive) crosses a homozygous gray female with a yellow male. F1 will be heterozygous gray.
- F1 x F1 produces:
  - F2 Genotypes: 1 X^G/Y (gray): 1 X^G/X^y (gray female): 1 X^y/Y (yellow male).
  - Phenotypes: roughly 3 gray: 1 yellow.
- Reciprocal Cross (yellow female X gray male): Results in a similar ratio.

Red-green color blindness: X-linked recessive trait. Cathy gives birth to a color-blind daughter.
- Is John justified?
  - No, John would not be justified as he could carry the color-blind gene since it is X-linked.
- If a color-blind son was born:
  - Yes, John would be justified in his claim of nonpaternity since color blindness in males comes from the X chromosome, passed from the mother.

Classic Hemophilia: An X-linked recessive disease.
Inheritance Possibility:
- YES: From His mother’s mother
- YES: From His mother’s father
- NO: From His father’s mother
- NO: From His father’s father
- Only maternal line can pass the X-linked gene for hemophilia.

Inheritance of Baldness: Z-linked recessive trait in chickens. Mating bald rooster with normal hen.
F1 Generation:
- Genotype proportions: Z^aZ^a (bald) vs Z^b Z^b (normal).
- F2 ratios to be calculated from interbreeding of F1.

Hypospadias: Birth defect caused by an autosomal dominant gene; no effects in female carriers.
Type of Trait: This defect is a sex-limited trait because it manifests in males only.

Offspring Ratios for Cock-Feathering:
- Cross of hh-hen feathered hen X hh-cock feathered rooster leads to F1 where males are affected showing different ratios depending on category.

Religious Law Consistency:
- The law regarding circumcision postulates that if two sons die from bleeding post-circumcision, further sons should not be circumcised, linking correctly to the X-linked hemophilia.
Genetic Principles: This law is consistent with genetic principles given the X-linked basis for hemophilia, affecting male progeny.