Download Genetics of Blood Types

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Genetics of Blood Types
The human blood types A, B, and O are inherited by multiple alleles. Multiple
alleles refer to three or more genes that occupy a single locus on a chromosome. Gene
IA codes for the synthesis of antigen (agglutionogen A), gene IB codes for the production
of antigen B on the red blood cells and gene i° does not produce any antigens.
Gene IA is dominant over io
Gene IB is dominant over i°
Gene IA and Gene IB are codominant;
Phenotypes
both expressed when they occur together
Possible Genotypes
Blood Problems: (Show your work- cross and square)
1. A man of blood type AB marries a woman of blood type A. What are the possible
blood types of their offspring if the woman's mother was blood type O?
2. Two parents, both heterozygous for blood type A, produce a child. What are the
chances that the child has blood type A?
3. Three brothers have blood types A, B, and O. What are the chances that a fourth
child of the same parents will have blood type AB?
4. A child with blood type O has a mother with blood type A and a father with blood
type B. The parental genotypes for blood types must be?
5. A couple has a child with type A blood. If one parent is type O, what are the
possible genotypes of the other parent?
6. A man with type O blood and a woman with type AB blood get married.
a. What is the probability that they will have a child with type A blood?
b. Suppose that one of the couple's children needs an operation. This
child has type B blood. Can the child safely receive a blood transfusion from
either parent? Explain.
7. Vincent has type A blood and his mother has type O blood. Christine has type B
blood and her father has type O blood.
a. What is Vincent's genotype?
b. What is Christine's genotype?
c. What genotype(s) might Christine's mother have?
d. Suppose Vincent and Christine get married. What is the probable
phenotypic ratio for their offspring? i '
,
e. What is the probable genotypic ratio for their offspring?
8. A case was brought before a certain judge in which a woman of blood group O
presented a baby of blood group O, which she claimed as her child, and brought a
paternity suit against a man of group AB whom she claimed was the father of the child.
What bearing might the blood type information have on the case? Show your work.
9. In a certain hospital two baby girls were born on the same day. The Jones named
their daughter Shirley, and the Smiths named their daughter Betty. As the proud
parents prepared to take their newborns home, Mrs. Jones suspected that there had
been a mix up, and that they did not have the right baby! The blood types of the babies
and the parents were
Mrs. Jones type A
Mr. Jones type A
Mrs. Smith type O
Mr. Smith type B
Baby Taken home by the Jones
type B blood
Baby Taken home by the Smiths
type O blood
Did the Jones really take home Shirley or do the Smiths have their baby?