Question

The disease allele for a certain disease is S. The normal allele is s. The disease is observed when a person has at least one copy of the disease allele, S. Which pattern of inheritance does the disease follow?

A. Codominant

B. Dominant

C. Polygenic

D. Recessive


I don't want the answer, I just need help. I don't know what the heq they are saying :<


pls and thx :>

Edit:
do you mind if I add two?

In horses, a single gene with two alleles determines skin color. The horse can be gray, white or appaloosa. An appaloosa horse is white with gray patches. Which of the following is true about alleles for color in horses?

The gray and white alleles are codominant.
The appaloosa and gray alleles are codominant.
The allele for white color is dominant over the gray color allele.
The allele for gray color is dominant over the white color allele.

Answer 1

The disease allele 'S' follows a dominant inheritance pattern, as the phenotype is expressed with only one copy of the allele. In horses, the gray and white alleles for skin color exhibit codominance, resulting in the appaloosa phenotype with both colors visibly expressed.

Step-by-step explanation:

Inheritance Patterns

The disease described in the question follows dominant inheritance because the presence of a single disease allele S results in the disease. This indicates that the allele for the disease ('S') is dominant over the normal allele ('s'). For the phenotype to be displayed in this scenario, just one copy of the 'S' allele is required, regardless of whether the individual is homozygous (SS) or heterozygous (Ss) for the trait.

Regarding the horse color, since an appaloosa horse displays a mix of gray and white patches, it indicates that neither color is completely dominant over the other and that the two alleles for color interact in a unique way. This is an example of codominance, where the gray and white alleles are expressed equally in the phenotype of the horse that is heterozygous for the skin color gene (possessing one allele for gray and one for white).