Here is the full question:
An albino corn snake is crossed with a normal colored corn snake. The offspring are all normal-colored. When the first generation progeny snakes are crossed among themselves, they produce 32 normal colored snakes and 10 albino snakes.
a. How do you know that only a single gene is responsible for the color differences between these snakes?
b. which of these phenotypes is controlled by the dominant allele?
c. a normal colored female snake is involved in a test cross. This cross produces 10 normal colored and 11 albina offspring. what are the genotypes of the parents?
Explanation:
First of all, in genetics, Phenotype are the observable physical properties of an organism; these include the organism's appearance, development, and behavior. An organism's phenotype can be determined by its genotype, which is the set of genes the organism carries, as well as by environmental influences on these genes.
Allele, which can also be called allelomorph, is any one of two or more genes that may occur alternatively at a given site on a chromosome. Alleles may occur in pairs, or we may have multiple alleles affecting the phenotype of a particular trait. The combination of alleles that an organism carries is its genotype. If the paired alleles are the same, the organism’s genotype is said to be homozygous for that trait. If they are different, the organism’s genotype is heterozygous. A dominant allele (A) will override the traits of a recessive allele (a) in a heterozygous pairing.
(a) In the question, we have two phenotypes seen in the second generation of this cross: normal and albino. Therefore, only one gene with two alleles is needed to control the phenotypes like colour of the snakes observed. The 3:1 ratio of these phenotypes in the F2 generation will be seen only if a single gene is involved.
(b) The allele controlling the normal phenotype (A) is dominant to the allele controlling the albino phenotype (a).
(c) The male parent’s genotype is aa. The normally colored offspring must receive an A allele from the mother, so the genotype of the normal offspring of the testcross is Aa. The albino offspring must receive an a allele from the mother, so the genotype of the albino offspring of the testcross is aa. Thus, the female parent must be heterozygous Aa.
