This worksheet gives students a chance to practice identifying genotypes on pedigree charts. The pedigrees focus on human genetic diseases, such as albinism, cystic fibrosis, tay-sachs, and sickle cell anemia. Some students do struggle with these charts, so I usually practice doing a few with them. If the parents are both heterozygous (Aa x Aa) many students will be confused about the genotype of an offspring who does not have the disease. In that case, if there isn’t enough information, it is acceptable to write the genotype as “AA or Aa.”
Sex-linked traits are not on this practice worksheet, since I reserve that for later lessons on sex-linkage. Intro level classes are shown a pedigree of a sex-linked chart but are not required determine genotypes in those cases.
Shown below is a very simple slide presentation I share with the intro classes, which also describes the diseases. Sickle cell anemia is a story-line thread that connects many of the lessons for that semester-long biology course. For example, they already learned about how a single change in DNA can lead to a change in the protein for hemoglobin.
Grade Level: 9-12
Time Required: 15 -20 minutes