Unpacking the Problem 44John and Martha are contemplating having children, butJohn’s brother has galactosemia (an autosomal recessivedisease) and Martha’s great-grandmother also had galactosemia. Martha has a sister who has three children, none ofwhom have galactosemia. What is the probability that Johnand Martha’s first child will have galactosemia?1. Can the problem be restated as a pedigree? If so, writeone.2. Can parts of the problem be restated by using Punnettsquares?3. Can parts of the problem be restated by using branchdiagrams?4. In the pedigree, identify a mating that illustratesMendel’s first law.5. Define all the scientific terms in the problem, and lookup any other terms about which you are uncertain.6. What assumptions need to be made in answering thisproblem?7. Which unmentioned family members must be considered? Why?8. What statistical rules might be relevant, and in whatsituations can they be applied? Do such situations existin this problem?9. What are two generalities about autosomal recessivediseases in human populations?10. What is the relevance of the rareness of the phenotypeunder study in pedigree analysis generally, and whatcan be inferred in this problem?11. In this family, whose genotypes are certain and whoseare uncertain?12. In what way is John’s side of the pedigree differentfrom Martha’s side? How does this difference affectyour calculations?13. Is there any irrelevant information in the problem asstated?14. In what way is solving this kind of problem similar tosolving problems that you have already successfullysolved? In what way is it different?15. Can you make up a short story based on the human dilemma in this problem?Now try to solve the problem. If you are unable to do so, tryto identify the obstacle and write a sentence or two describingyour difficulty. Then go back to the expansion questions and seeif any of them relate to your difficulty
Unpacking the Problem 44
John and Martha are contemplating having children, but
John’s brother has galactosemia (an autosomal recessive
disease) and Martha’s great-grandmother also had galactosemia. Martha has a sister who has three children, none of
whom have galactosemia. What is the probability that John
and Martha’s first child will have galactosemia?
1. Can the problem be restated as a pedigree? If so, write
one.
2. Can parts of the problem be restated by using Punnett
squares?
3. Can parts of the problem be restated by using branch
diagrams?
4. In the pedigree, identify a mating that illustrates
Mendel’s first law.
5. Define all the scientific terms in the problem, and look
up any other terms about which you are uncertain.
6. What assumptions need to be made in answering this
problem?
7. Which unmentioned family members must be considered? Why?
8. What statistical rules might be relevant, and in what
situations can they be applied? Do such situations exist
in this problem?
9. What are two generalities about autosomal recessive
diseases in human populations?
10. What is the relevance of the rareness of the
under study in pedigree analysis generally, and what
can be inferred in this problem?
11. In this family, whose genotypes are certain and whose
are uncertain?
12. In what way is John’s side of the pedigree different
from Martha’s side? How does this difference affect
your calculations?
13. Is there any irrelevant information in the problem as
stated?
14. In what way is solving this kind of problem similar to
solving problems that you have already successfully
solved? In what way is it different?
15. Can you make up a short story based on the human dilemma in this problem?
Now try to solve the problem. If you are unable to do so, try
to identify the obstacle and write a sentence or two describing
your difficulty. Then go back to the expansion questions and see
if any of them relate to your difficulty
Step by step
Solved in 2 steps with 1 images
