1) Consider two bloodpolymorphisms that humans have in addition to the ABO syste
ID: 5165 • Letter: 1
Question
1) Consider two bloodpolymorphisms that humans have in addition to the ABO system. Twocodominant alleles LM and LN determine the M,N, and MN blood groups. The dominant allele R of adifferent gene causes a person to have the Rh+ (rhesuspositive) phenotype, while people homozygous for the recessiveallele r have Rh- blood type. Two men took apaternity dispute to court, each claiming three children to be hisown. The blood groups of the men, the children, and their motherwere as follows:
Person
Blood group
Husband
O
M
Rh+
Wife’s lover
AB
MN
Rh-
Wife
A
N
Rh+
Child 1
O
MN
Rh+
Child 2
A
N
Rh+
Child 3
A
MN
Rh-
From this evidence, determine the father of each child. Explainyour reasoning. If the evidence is not adequate to determine thefather, explain why not.
Person
Blood group
Husband
O
M
Rh+
Wife’s lover
AB
MN
Rh-
Wife
A
N
Rh+
Child 1
O
MN
Rh+
Child 2
A
N
Rh+
Child 3
A
MN
Rh-
Explanation / Answer
Two codominant alleles LM and LN determinethe M, N, and MN blood groups
M, blood group-GENOTPYE -----MM
N, blood group -GENOTPYE -----NN
MN blood group- GENOTPYE -----MN
========================================
dominant allele R of a different gene causes a personto have the Rh+ (rhesus positive) phenotype, whilepeople homozygous for the recessive allele r haveRh- blood type
Rh+ (rhesus positive---------- GENOTPYE - RR, R r
Rh--------------------------------------------------------------rr
A- GENOTPYE -----AA,AO ALLELES
B-----GENOTPYE ----- BB,BO
AB GENOTPYE -----AB
O GENOTPYE-----OO
Husband O M Rh+
GENOTPYE OO MM R R, OR R r
Wife’s lover
AB-------------------MN--------------Rh-
GENOTPYE AB-------------------MN--------------rr
=====================================
Wife A-----------N----------------Rh+
==============================================
GENOTPYE -----
Child 1
O-------------MN--------------Rh+
The first child willhave the husband for a father as the O blood group has comefrom him only.
Child 2
A-------------N--------Rh+
The second child will have the lover as a father as the N bloodgroup will come from him only.
==============================================
Child 3
A---------------MN==========Rh-
The third child could have either the husband or the lover asthe father.
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