Those Old Kentucky Blues
Unit 7 Biology lab
The Blue People of Troublesome Creek
Name ___________________________________ Block ____ Date ______________________
Use this sheet to record your notes as you work through each section of this lab. You will use
these notes and additional research to write up a discussion due next week.
Part 1
1. What two hypotheses did your group come up with to explain why these people were blue?
2. How did you propose you could test your hypotheses?
3. After the class discussion, explain how other groups’ ideas helped you to reconsider aspects
of your answers to questions 1 and 2.
Part 2
1. Construct your pedigree on a separate piece of paper. Use pencil or erasable pen (!) so that
you can make changes as you think through the relationships and genotypes of different family
members.
2. Evaluate your pedigree. Can you decide if “blueness” is a heritable trait?
3. If so, what pattern of inheritance do you suspect? If not heritable, explain how you think this
disease is caused and why.
4. Make sure you have provided allele designations for each person in the pedigree. Add names
if known.
Part 3 –
1. Explain the relationship of the enzyme NADH diaphorase (also called NADH dependent
methemoglobin reductase) to the protein hemoglobin.
2. After examining the graph in figure 2, explain what the three lines in this figure tell us in
terms of the relationship between NADH diaphorase activity and the blue skin phenotype?
3. Provide genotype designations for:
blue people parents of blue people people with normal skin color –
4. After evaluating the enzyme graph, what is the pattern of inheritance at the molecular level
(NADH diaphorase enzyme level, not the skin color level)?
Why are there 3 phenotypes at the NADH diaphorase enzyme level vs. 2 phenotypes seen at the
skin color level?
Discussion. In a typed discussion, address the following in a numbered format and staple to this
labsheet:
1. Describe how your interpretation of the cause/pattern of inheritance of the phenotype in the blue
people changed as you added different types of evidence from Part I – III (includes protein
molecular level-specific inheritance pattern). Be specific.
2. What protein enzyme caused this phenotype? What does this protein normally do? What
happens when it is not working? How does this cause the phenotype?
3. How could a change in the amino acid sequence affect the protein function? Explain in detail.
(Review protein structure and enzymes to help you think about this)
4. What were possible genotypes for people who were blue, parents of blue people (who perhaps
were blue for a few weeks at birth), and people who were not blue?
5. What is the relationship between DNA, genes, proteins, and traits (phenotypes)? Relate
this to the specific case of the blue people.