Chapter 4: Problem 22

Five human matings \((1-5),\) identified by both maternal and paternal phenotypes for \(\mathrm{ABO}\) and \(\mathrm{MN}\) blood-group antigen status, are shown on the left side of the following table: Each mating resulted in one of the five offspring shown in the right-hand column (a-e). Match each offspring with one correct set of parents, using each parental set only once. Is there more than one set of correct answers?

Short Answer

Expert verified

Question: Match each offspring with the correct set of parents based on their ABO and MN blood-group antigen status. Offspring: a) B_MM b) O_MN c) A_NN d) A_MM e) B_MN Parental Mating Pairs: Mating 1: IAi x IBi, MM x MN Mating 2: IAIA x IAi, MN x NN Mating 3: IAi x IBi, MM x MN Mating 4: IAi x IBi, MM x MN Mating 5: ii x ii, MN x NN Provide the correct match of offspring to parental mating pairs.

Step by step solution

For the ABO blood group, there are three alleles: A, B, and O. The A and B alleles are codominant, meaning that if an individual has both A and B, their blood type is AB. O is a recessive allele, so an individual with OO will have type O blood. For the MN blood group, two alleles are found, M and N, which are also codominant. Thus, if an individual has both, their blood type for the MN antigen status is MN. #Step 2: List possible offspring blood groups for each mating#

Calculate all possible blood types that offspring can have, based on the parents' phenotypes. Here are the possible offspring blood groups for each mating pair: Mating 1: \(\mathrm{ABO}\): IAi, IBi \(\mathrm{MN}\): MM, MN - offspring blood groups: A_MM, A_MN, B_MM, B_MN Mating 2: \(\mathrm{ABO}\): IAIA, IAi \(\mathrm{MN}\): MN, NN - offspring blood groups: A_MN, A_NN Mating 3: \(\mathrm{ABO}\): IAi, IBi \(\mathrm{MN}\): MM, MN - offspring blood groups: A_MM, A_MN, B_MM, B_MN Mating 4: \(\mathrm{ABO}\): IAi, IBi \(\mathrm{MN}\): MM, MN - offspring blood groups: A_MM, A_MN, B_MM, B_MN Mating 5: \(\mathrm{ABO}\): iI, iI \(\mathrm{MN}\): MN, NN - offspring blood groups: O_MN, O_NN #Step 3: Assign offspring to parental pairs#

The order of assigned numbers corresponds to the order of offspring a-e: a) B_MM - can only be produced by Mating 1, 3, or 4. We assign Mating 1 to offspring a. b) O_MN - can only be produced by Mating 5, so we assign Mating 5 to offspring b. c) A_NN - can only be produced by Mating 2, so we assign Mating 2 to offspring c. d) A_MM - can only be produced by Mating 3 or 4, but as Mating 3 is the only available option, we assign it to offspring d. e) B_MN - can only be produced by Mating 4, so we assign Mating 4 to offspring e. #Step 4: Check for multiple correct answers.

Since there are no alternative assignments for each offspring that satisfy the parental phenotypes, there is only one correct set of parent-offspring matches.