GENETIC WORKSHEET
INET Lab
Student:
Email:
Date:
Please complete and submit this worksheet to earn 5 points.
1. There are 3 alleles controlling the ABO blood types. IA and IB are codominant genes so that the combination IAIB produces the AB blood type. The third allele, (i) is recessive to the other two alleles. Show your work for each cross.
Indicate which of these parents could produce the given child. Fill in all the blank spaces.The first one is provided with answers as an example.
(HINT: Do not forget that a heterozygous versus a homozygous blood type may yield different results.)
| | IA | IB | ||
| IA | IA IA | IA IB | ||
| i | IA i | IB i | ||
| b) | Parent | Child |
| A x O |
| | Allele? | Allele? | ||
| Allele? | | | ||
| Allele? | | | ||
| | Allele? | Allele? | ||
| Allele? | | | ||
| Allele? | | | ||
| e) | Parent | Child |
| B x B |
| | Allele? | Allele? | ||
| Allele? | | | ||
| Allele? | | | ||
Autosomal Disorder
2. The allele for albinism (a) is recessive to the allele for normal pigmentation (A). A normally pigmented woman whose father is an albino marries an albino man whose parents are normal. They have three children, two normal and one albino. Give the genotypes for each person listed. Prove your answer.
Show the cross of the paternal grandparents.
(HINT: What must their genotypes be to produce and albino child?)
What are the possible genotypes of the maternal grandmother?
| | Allele? | Allele? | ||
| Allele? | | | ||
| Allele? | | | ||
Show the cross of the mother and father.
3. In horses, black coat color is influenced by the dominant allele (B), and chestnut coat color by the recessive allele (b).
What color horse would you use to find out the genotype of a black trotter?
Give the genotype and phenotype. Show your work and discuss the reason you would know the genotype of the black horse.
Possible Allele Pairings with Homozygous Dominant Trotter
| F1 offspring probabilities: |
Possible Allele Pairings with Heterozygous Trotter
| F1 offspring probabilities: |
Reasoning:
4. In Drosophila, the fruit fly, white eyes are determined by a recessive X-linked gene, and the wild-type or normal brick-red eyes are due to its dominant allele. Use symbols of the following types: XrY = a white-eyed male; XRXR = a homozygous normal red female.
What offspring can be expected from a cross of a white-eyed male and a homozygous normal female?
Show the genotypes and list the phenotypes of the F1 offspring.
F1 Cross
F1 offspring probabilities:
Now, cross the F1 offspring. Show the genotypes and list the phenotypes of the F2 offspring.
F2 Cross
F2 offspring probabilities:
| Male | Female | |
| Red-Eyed | ||
| White-Eyed |
