Activity 2 Cells and Disease

Where do you think cells are involved in life processes? Why do you think scientists and doctors study cells? Students may know that cells make up skin, are involved in reproduction, or other facts. Students are likely to say doctors study cells to see if something is wrong or if someone is sick. See your Teacher’s Edition for this activity for other suggestions of what background knowledge students may have.

Read the introduction. What is a disease? What is a microbe? A disease is any breakdown in the structure or function of an organism. A microbe is a microscopic organism usually one that produces a disease

PATHOGEN Any disease causing organism Bacteria… viruses… fungi… protists

Challenge How do observations of cells help doctors and scientists diagnose and study diseases?

Assessing the Patients & Diseases Read the patient histories (pg. 162-163). Do you think these 2 patients suffer from the same disease? Why or why not? Look at the table of possible diseases. Read through the information Can you identify the disease that each patient has? Why or why not? You may wish to stop the class at step 4 and have the students share their observations of the blood samples. They should notice that Patient A’s sample has fewer cells than normal blood and some are oblong or boomerang-shaped. They should also notice that Patient B’s red blood cells look normal, but purplish objects with black dots appear among the red blood cells. See your Teacher’s Edition for further suggestions on providing support to students in making their diagnoses.

What symptoms do all of the diseases have in common? Do you think a doctor would be able to diagnose any of theses diseases based on the patient’s symptoms?

Using a Microscope Review microscope use as needed. For more support see Teacher Resources II: Diverse Learners, especially Science Skills Transparency 3, “How to Use a Microscope” and Science Skills Student Sheet 6, “Parts of a Microscope.”

What diagnosis did you give to Patient A, and what was your evidence? What diagnosis did you give Patient B, and why? Patient A has sickle cell disease. Some of Patient A’s blood cells were the long, thin, banana-shape characteristic of this disease, and the patient’s symptoms match those of sickle cell disease. Patient B has malaria because although her blood cells look normal, among them are irregularly shaped objects with dark dots inside. The patient’s symptoms match those of malaria. For more information on these diseases and how they affect blood cells see your Teacher’s Edition for this activity.

ANALYSIS 1. Comparing each patient’s blood sample to normal human blood, describe abnormalities that you observed 2. Which patient has an Infectious Disease? How do you know?

Analysis 3 Observe the diagrams below. Which patient would you diagnose with sickle cell disease? Explain, using evidence from this activity. Patient 1 Patient 2 For suggestions on having a class discussion about this Analysis question see your Teacher’s Edition for this activity. This is an example of how the structure of a cell helps it perform its function. If the structure is damaged in some way, the cell is no longer able to perform its function. A sample student response can be found in your Teacher’s Edition for this activity.

Analysis 4 Based on the diagrams, how does the shape of normal red blood cells help them perform their function? How does the shape of sickled red blood cells prevent them from performing their function?

Analysis 5 How do microscope observations of cells help doctors and scientists diagnose and study diseases? Give specific examples from this activity. Students’ responses to Analysis question 4 can be scored with the Understanding Concepts (UC) Scoring Guide. If appropriate, introduce the UC assessment variable here. See your Teacher’s Edition for more information on how to do this. A sample student response can be found in your Teacher’s Edition for this activity.

NORMAL HUMAN BLOOD SMEAR

SICKLE CELL ANEMIA

MALARIA

POLYCYTHEMIA VERA

SPHEROCYTOSIS

SPHEROCYTOSIS

CASE STUDY: MALARIA Read the case study in your book beginning on p. 167 Get some sticky notes and use the READ…THINK…TAKE NOTE strategy (see next slide for guidelines) After reading the passage…discuss your notes with your partner

For more information on using this literacy strategy with your students see your Teacher’s Edition for this Activity and see Teacher Resources III: Literacy. These guidelines can also be found on Literacy Transparency 3, “Read, Think, and Take Note.” Tell students they will read six case studies during the unit. Review Student Sheet 2.1, “Disease Information,” with your students and be sure they are aware that they will use the information from the case studies in the last two activities of the unit.

What are the trade-offs of using insecticides to kill the mosquitoes? Analysis 6 From what you learned about malaria in the case study: What are the trade-offs of using insecticides to kill the mosquitoes? Remember: A trade-off is an exchange of one thing in return for another, giving up something that is a benefit or advantage, in exchange for something that may be more desirable. What are the benefits of using insecticides to kill mosquitoes that might be carrying Plasmodium? Analysis Question 5b is a Quick Check assessment to ensure that students understand the term, and can identify trade-offs, which is a component of the Evidence and Trade-offs (ET) scoring variable. If appropriate, introduce the ET assessment variable here. See your Teacher’s Edition for more information on how to do this. A sample student response can be found in your Teacher’s Edition for this activity.

Analysis 7 Based on the malaria cse study, how does resistance develop in a population of disease-causing microbes?