Important Note: Teachers may want to give the Pre-Test at least a day before teaching the lesson to assess the students' prior knowledge and identify possible vocabulary foci.
1. The teacher will engage the students in a discussion about any previous knowledge of an inherited disease and a Punnett square. The teacher may want to also use a KWL chart to assess knowledge before, during, and after this lesson. Optional KWL Chart
Suggested Engagement Questions:
How can someone get an inherited disease?
Is Sickle Cell Anemia an inherited disease? Why? or Why Not?
What is a Punnett square?
2. Students will watch a video from the American Society of Hematology that illustrates a real life example of an inherited disease.
Note: This short clip should be used as an example of an inherited disorder that can be determined through traits from parents.
3. After reviewing the video, the teacher will replay the video and pause at various segments in the video clip to assess/facilitate learning. The teacher will clarify unclear or confusing information as needed for each segment.
Suggested Engagement Questions:
Did the video mention blood flow? Why is this important?
Did the patient have Sickle Cell Anemia?
What does this suggest about the parents?
4. The teacher may facilitate an additional discussion using an interactive PowerPoint. (Optional PowerPoint--see uploaded attachments for document.)
5. The teacher will walk around the room with 2 bowls or large noodle chromosome structures labeled mother and father, each containing alleles (letters). The students must select one pair from each bowl. Each student will also receive a punnett square and complete it to determine their genotype.
The teacher will model step #5 and walk around and monitor the students as they complete this task. Additional clarification will be provided as needed.
6. Once the students have determined their genotype, they will write it on their name tag and place it on their shirts. Based upon their genotypes, the students will then be divided into five groups of 6 students each. Each group will have 2 heterozygous (Ss), 2 homozygous recessive (ss), and 2 homozygous dominant (SS) genotypes per group.
The teacher will walk around and monitor the students as they complete this task, additional clarification will be provided as needed. (make sure at-risk students are paired with proficient students)
7. The students will then proceed to Station 1: Build Your Hemoglobin Protein Station. At this station, the students will use the chemistry molecule model set (colored balls that represents amino acids) to build the protein hemoglobin. The teacher will model and show a visual example. (See attachment entitled Teacher Notes for pictures.)
Notes: (Black = glutamate/normal, Red = Valine/Sickle cell substitution)
8. After building their protein (hemoglobin), the students will proceed to Station 2: The Red Blood Cell Station to demonstrate how a simple change in protein structure can have a devastating effect on protein function.
The students will exchange their hemoglobin (model set) for the appropriate red blood cell shape. The Red Hots represent normal red blood cells composed of normal hemoglobin. The banana Runts represent sickle-shaped red blood cells composed of abnormal hemoglobin. The students with heterozygous (Ss) genotype will obtain 2 Red Hots and 2 banana Runts. The students with homozygous recessive (ss) genotype will obtain 4 banana Runts. The students with homozygous dominant (SS) genotypes will obtain 4 Red Hots.
Each group will take three 25 mL Erlenmeyer flasks and their shaped red blood cells. (See attachment entitled Teacher Notes for pictures.)
9. Using their 25 mL Erlenmeyer flasks, the students will conduct the hands on demonstration of blood flow. The students will place red blood cells in the appropriate genotype labeled flask. The students will attach a conical tube representing blood vessels to the neck of flask using tape, and rock back and forth 5 times.
They will record their observations in a table or science journal. Crescent-shaped blood cells clog blood vessels, impeding blood flow. (See attachment entitled Teacher Notes for pictures.)
10. After all the stations have been completed, the teacher will tell the students to display their results/journals on their tables, and do an additional "chat and check" with each group and give each group an opportunity to ask questions if needed.
11. The teacher will provide each group with a digital camera or iPad and allow them to take pictures of each item they made in each station.
12. The students will use the pictures to create a photo journal and summarize what each picture represents or illustrates.
13. The teacher will provide the groups with a time they can share their items and journals with their classmates (may be completed on a different day).