As easy as one, two … pee?
A study of Alkaptonuria
Teacher Notes and Lab Set-up
Overview and concepts
Overview
This lesson is designed to increase the student’s knowledge about genetic inheritance and
medical problem solving. Students test samples from a family afflicted with alkaptonuria and
construct a pedigree to display the inheritance.
Grade Level
High school (9-12)
Concepts covered
Pedigrees
Modes of inheritance
Genetics diseases
Genetic database research
Prior knowledge required
Genotypes/phenotypes
Pedigrees
Basic modes of inheritance
Learning objectives
Students will be able to identify symptoms of a genetic ndiseases using the OMIM database.
Students will be able to explain the mechanisms and causes of the genetic disease.
Activity Notes
Time frame
This activity is designed to take two class periods (~50 min). The first class period is to do
disease research. The second class period is to perform the lab.
Teaching tips
-The iodine should react with the starch in the solution and turn a dark brown, mimicking the
presence of Alkaptonuria.
-The sugar in the beakers is used to mimic the cloudy appearance of the cornstarch in the other
beakers.
-Teachers may need to stir the solutions before each period so the starch doesn’t settle to the
bottom of the beakers.
-This activity certainly gets the attention of kids with the “gross factor” of handling urine,
however it may be necessary to reassure students that it is fake urine and it is safe to handle.
(Technically speaking, this urine is drinkable!)
Extensions
- Students will struggle with the fact that we were not able to test all the family members and
create a conclusive pedigree. Teacher can use that a good opportunity to introduce that medical
problem solving often includes gaps in knowledge that scientists must deal with and compensate
for.
Resources
"AKU Society." AKU Society. Web. 19 Apr. 2012. <http://www.alkaptonuria.info/>.
"Alkaptonuria." Genetics Home Reference. 16 Apr. 2012. Web. 19 Apr. 2012.
<http://ghr.nlm.nih.gov/condition/alkaptonuria>.
"Alkaptonuria: MedlinePlus Medical Encyclopedia." U.S National Library of Medicine. U.S. National
Library of Medicine. Web. 19 Apr. 2012.
<http://www.nlm.nih.gov/medlineplus/ency/article/001200.htm>.
Lab Set-Up
Each lab station should have a test tube rack, 6 test tubes, one dropper bottle of iodine
(Alkapotnuria testing solution), and a volumetric pipette.
The teacher should set up 6 urine samples in 500 ml beakers with ingredients as follows:
400 ml water
Beaker 1
Grandpa Orina
Positive
Beaker 2
Grandma Orina
Beaker 3
Pappy Luis
Beaker 4
Mr. Orina
Beaker 5
Mrs. Orina
Beaker 6
Rosa
10 drops yellow food coloring
1 red drop red food coloring
3 spoonfuls of corn starch (fully dissolved)
400 ml water
10 drops yellow food coloring
1 red drop red food coloring
3 spoonfuls of sugar (fully dissolved)
400 ml water
10 drops yellow food coloring
1 red drop red food coloring
3 spoonfuls of corn starch (fully dissolved)
400 ml water
10 drops yellow food coloring
1 red drop red food coloring
3 spoonfuls of sugar (fully dissolved)
400 ml water
10 drops yellow food coloring
1 red drop red food coloring
3 spoonfuls of corn starch (fully dissolved)
400 ml water
10 drops yellow food coloring
1 red drop red food coloring
3 spoonfuls of sugar (fully dissolved)
Negative
Positive
Negative
Positive
Negative