1. How does each of the following processes illustrate the interaction of cell components?

     a. maintaining the integrity of the red blood cell membrane

     b. the ability of muscle cells to withstand the force of contraction

     c. signal transduction

     d. cell adhesion in leukocyte trafficking

2. Describe how dynein and dystrophin are vital for the functioning of certain cells, even though they are not very abundant.

3. Liver cells are packed with glucose. What mechanism could be used to transport more glucose into a liver cell? Why would only this mode of transport work?

4. A drop of a 5% salt (NaCl) solution is added to a leaf of the aquatic plant Elodea. When the leaf is viewed under a microscope, colorless regions appear at the edges of each cell as the cell membranes shrink from the cell walls. What is happening to these cells?

5. Would a substance that destroys the integrity of the blood-brain barrier be dangerous? Why or why not?

Additional Questions and Terms

1. For the following medical conditions discussed in the chapter, describe how the defect at the molecular and/or cellular level explains the symptoms:

2. Many drugs used to treat cancer stop working because of a protein in the cell membranes of some cancer cells, called P-gp. This protein pumps many types of drugs out of the cell membrane before they can enter the cytoplasm, causing a phenomenon called "multidrug resistance." P-gp requires ATP to function, and it continually cycles from its site of synthesis in the cytoplasm to the cell membrane, carried within vesicles. P-gp is recycled when vesicles bud inward from the cell membrane.

3. In many species , sperm cells have surface proteins that bind to receptor molecules on the egg cell's surface. Use this information to suggest two possible methods of birth control.