Respuesta :
Answer: a) Cch x Ccch
b) Ccch x Cc
c) Cch x cchch
d) cchc x chc
Explanation:
Data:
- Coat color in rabbits is under the control of a single gene with
four alleles: C (full gray color); cch (chinchilla, light gray); ch
(Himalayan, white with black extremities); and c (albino, absence
of pigmentation).
- The dominance hierarchy is represented as: C >cch > ch > c.
Possible genotypes:
- For full gray color: CC (Gray), Ccch (Gray-2), Cch (Gray-1), Cc (Gray-3). The allele "C" dominates over the other three alleles, so in every combination where "C" is present, the animal will be fully grayed.
- For light gray color/Chinchilla: cchcch (Chinchilla), cchch (Chinchilla-1), cchc (Chinchilla-2). The allele "cch" dominates over "ch" and "c", but not over "C". So if the allele "C" is combined with "cch", the animal will be fully grayed, but in any other combination with "cch", the animal will be light grayed.
- For white with black extremities/Himalayan: chch (Hymalayan), chc (Hymalayan-1). The allele "ch" that determines the Himalayan color is only dominant over the allele "c". But in combination with any other allele, "ch" behaves as a recessive one.
- For albino: cc. In the presence of any of the other alleles, the allele "c" always behaves as a recessive one. The only possibility of getting an albino animal is if "c" combines with another "c".
Crosses:
a) Gray-1 x gray-2
3/4 gray : 1/4 chinchilla
Parental) C ch x C cch
Gamates) C ch C cch
Punnet Square) C cch
C CC Ccch
ch Cch cchch
F1 Genotype) 1/4 CC
1/4 Cch
1/4 Ccch
1/4 cchch
F1 Phenotype) 3/4 Fully Gray animals (CC, Cch, Ccch)
1/4 Chinchilla animals (cchch)
b) Gray-2 x gray-3
3/4 gray : 1/4 chinchilla
Parental) C cch x C c
Gamates) C cch C c
Punnet Square) C cch
C CC Ccch
c Cc cchc
F1 Genotype) 1/4 CC
1/4 Cc
1/4 Ccch
1/4 cchc
F1 Phenotype) 3/4 Fully Gray animals (CC, Cc, Ccch)
1/4 Chinchilla animals (cchc)
c) Gray-1 x chinchilla-1
1/2 gray : 1/4 chinchilla : 1/4 himalayan
Parental) C ch x cchch
Gamates) C ch cch ch
Punnet Square) C ch
cch Ccch cchch
ch Cch cchch
F1 Genotype) 1/4 Ccch
1/4 Cch
1/4 cchch
1/4 chch
F1 Phenotype) 2/4=1/2 Fully Gray animals (Ccch, Cch)
1/4 Chinchilla animals (cchch)
1/4 Himalayan animals (chch)
d) Chinchilla-2 x himalayan
1/2 chinchilla : 1/4 himalayan : 1/4 albino
Parental) cchc x chc
Gamates) cch c ch c
Punnet Square) cch c
ch cchch chc
c cchc cc
F1 Genotype) 1/4 cchch
1/4 cchc
1/4 chc
1/4 cc
F1 Phenotype) 2/4=1/2 Chinchilla animals (cchch, cchc)
1/4 Himalayan animals (chc)
1/4 Albino animals (cc)
