Analise Williams : GENETICS PROBLEMS

For each of the diploid genotypes presented below, determine the genetic make up for all of the possible gametes that would result through the process of meiosis. Remember, each egg or sperm must have one of each letter. That letter can be upper or lower case.

For each of the following, state whether the genotype of a diploid or haploid cell is represented.

Yellow guinea pigs crossed with white ones always produce cream colored offspring. Two cream colored guinea pigs when crossed produced yellow, cream and white offspring in the ratio of l yellow: 2 cream: l white. Explain how are these colors inherited? No calculations needed! Name the type of inheritance this represents.

This is an example of incomplete dominance because this alleles does not follow the dominant/recessive patterns.

In sheep white is due to a dominant gene (B), black to its recessive allele (b). A white ewe mated to a white ram produces a black lamb. What are the genotypes of the parents? You might need to construct Punnet squares experimenting with different crosses to come up with this answer. Name the type of inheritance this represents.

The genotypes of the parents are Bb and Bb and this example is a dominant recessive allele.

In peas, yellow color (G) is dominant to green color (g). A heterozygous yellow is crossed with a green. What is the expected phenotype ratio of the offspring? Name the type of inheritance this represents.

Gg is the phenotype with a ratio of 50/50 in being yellow or green. The type of inheritance is dominant-recessive.

White color (Y) is dominant to yellow color (y) in squash. A heterozygous white fruit plant is crossed with a yellow fruit plant. What is the expected phenotype ratio of the offspring? What is this type of inheritance called?

Yy is the phenotype with a ratio of 50/50 in being White or Yellow. The type of inheritance is dominant-recessive.

In certain flowers, a cross between homozygous red and a homozygous white will always result in a pink flower. A cross is made between two pink flowers. What is the predicted phenotype ratio of the colors red, pink and white appearing in the offspring? What is this type of inheritance called.

The phenotype ratio of red, white and pink is 1:1:2. The inheritance type is dominant recessive.

In humans, the condition for normal blood clotting dominates the condition for non-clotting or hemophilia. Both alleles are linked to the X chromosome. A male hemophiliac marries a woman who is a carrier for this condition. In this respect, a carrier is a woman who has an allele for normal blood clotting and an allele for hemophilia. What are the chances that if they have a male child he will be normal for blood clotting? What is this type of inheritance called?

The chances for 50/50 for the child to have normal blood clotting. This type of inheritance is called Sex-linked inheritance.

A person with an allele for type A blood and type O blood marries someone with an allele for type B blood and type O blood. List the types of offspring they could have and the probability for each blood type in the offspring. (A allele = IA, B allele = IB, O allele = i) What is the expected phenotype ratio of the offspring? What is this type of inheritance called?

The phenotype ratio of offspring would be 1:4; A, B, AB, O. The inheritance type is codominance.

Skin color in humans becomes darker by the number of dominant alleles; AABBCC have the darkest skin and aabbcc have the lightest skin. Place these genotypes in sequence according to the color of skin expected for each. Place the darkest skin first. What is this type of inheritance called?

Genotypes: AaBbCc, AAbbcc, aabbCc, AaBBCc, AaBBCC.

AaBBCC, AaBBCc, AaBbCc, AAbbcc, aabbCc. This type of inheritance is polygenic.

Analise Williams