Cells Teaming Up

This is a 16-page comic explainer that deepens students' understanding of one innovative advantage of multicellular organisms: immune response. The comic dramatizes how multicellular cooperation plays out at a cellular level. Assigning different cells distinct characterizations and using humor to engage students, it depicts a simplified bacterial infection. The comic stars a cast of human cells whose behavior offers an entertaining and useful review about how cells work together for immune response when faced with an invasion by single-celled infectious opponents. In contrast, all the pathogenic bacteria in the comic are alike; they don’t use the same kind of division of labor as multicellular organisms.

Students stay on task best when reading this out loud with at least one other student.

Paraphrase:

I'll give you 40 minutes to read this comic with a partner. Take turns reading panels.

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When the class finishes reading, ask students to answer these questions.

There are more comprehension questions than usual on this list. You can assign each student one or two questions or treat the nine questions as a comic scavenger hunt.

Possible answers:

1. Examples of specialization by human cells in the comic could include nerve cells, macrophage, neutrophils, dendritic cells, skin cells, red blood cells, fibroblast, and lymphocytes
2. Macrophages identify germs by checking cell membranes for molecules that germs would have. (Receptor cells on macrophages fit the shapes of molecules that are characterize germs.)
3. The macroscopic signs of inflammation are redness, heat, swelling, and pain. White blood cells like macrophages help trigger inflammation with chemical signals. When epithelial cells that make up blood vessels get those signals, they change their shape, widening the vessels to allow more blood flow (which causes redness and heat), and allowing more fluid out into the infected area (causing swelling). The swelling causes pressure. The pressure, and also the initial chemical signs of infection, cause nerve cells to carry pain signals to the brain.
4. Pus is made mostly of dead neutrophils.
5. Cells communicate using chemical signals. (Nerve cells also pass electrical signals along their membrane, so that would be an acceptable student answer; but although this comic doesn’t go into detail, even a nerve cell uses a chemical signal to tell the next nerve cell to initial its electrical signal.)
6. Two ways germs can do damage to the cells in people are using up their food and leaving unhealthy waste.
7. Antibody molecules attach to germ surfaces. Antibodies can then interfere with germs’ functioning, make germs stick together, and encourage white blood cells to eat the germs faster.
8. The immune system takes molecules from the germs themselves (antigen), and chooses a lymphocyte that makes exactly the right antibody to attack that antigen. (An antigen-presenting white blood cell like a dendritic cell helps show antigen to lymphocytes.)
9. It is important for the immune system to keep a lookout in all those places because the areas where macrophages are concentrated are exactly the places where stuff from outside the body (including stuff passing through the digestive system) is most likely to get into the body. These surfaces are where germs are most likely to attack.