In dogs, the gene for black hair dominates over coffee-colored hair, and the gene for short hair over long.

In dogs, the gene for black hair dominates over coffee-colored hair, and the gene for short hair over long. the hunter bought a black short-haired dog and wants to make sure that it does not carry the coffee-colored and long-haired genes. What kind of a tailor by phenotype and genotype should be chosen for crossing in order to check the genotype of the purchased dog?

Let’s designate the gene that causes the development of black hair in dogs as C, then the gene for coffee wool will be designated as c.

Let’s designate the gene that causes short hair in dogs as P, then the gene for long dog hair will be p.

To determine the purity of the breed of the purchased dog, the hunter can resort to a special type of crossing called the analyzing one. To conduct it, a dog is needed – a partner with long coffee-colored hair.

Such a dog will have the digomozygous ccpp genotype, which is necessary for both recessive traits. It will produce the same type of sex cells – cр.

If the dog bought by the hunter is purebred, then its genotype will be recorded as CCPP. Such a dog will only produce sex cells of the СР.

In the offspring, all puppies will be СсРр, that is, have short black hair.

If a dog carries genes for recessive traits in its genotype, then there will certainly be puppies in the offspring that exhibit them. A dog that is not a purebred dog may have genotypes: CcPp, CCPP, CcPP.

Let’s say the purchased dog is diheterozygous – CcPр. It produces sex cells cp, cp, cp and cp. An analyzing cross will give the following result:

coffee-colored puppies with long hair (ssrr) – 25%;

black shorthaired puppies (СсРр) – 25%;

black puppies with long hair (Ссрр) – 25%;

coffee-colored short-haired puppies (ссРр) – 25%.