Review Exercises

4. Exposure to tobacco smoke causes cilia to cease moving and degenerate. Why might this explain why tobacco smokers have an increased incidence of respiratory infections?

5. How would you explain the function of phagocytic cells to a patient with a bacterial infection?

6. How is knowledge of how cell division is controlled important to an understanding of each of the following?

a. growth b. wound healing c. cancer

7. Why are enlarged lysosomes a sign of a serious illness?

1. Use specific examples to illustrate how cells vary in size.

2. Describe how the shapes of nerve, epithelial, and muscle cells are well suited to their functions.

3. Name the major components of a cell, and describe how they interact.

4. Discuss the structure and functions of a cell membrane.

5. How do cilia, flagella, and cell adhesion molecules move cells?

6. Distinguish between organelles and inclusions.

7. Define selectively permeable.

8. Describe the chemical structure of a membrane.

9. Explain how the structure of a cell membrane determines which types of substances it admits.

10. Explain the function of membrane proteins.

11. Describe three kinds of intercellular junctions.

12. Describe the structures and functions of each of the following:

a. endoplasmic reticulum b. ribosome c. Golgi apparatus

d.

mitochondrion

e.

lysosome

f.

peroxisome

g.

cilium

h.

flagellum

i.

centrosome

j.

vesicle

k.

microfilament

l.

microtubule

13. Describe the structure of the nucleus and the functions of its contents.

14. Distinguish between diffusion and facilitated diffusion.

15. Name three factors that increase the rate of diffusion.

16. Explain how diffusion aids gas exchange within the body.

17. Define osmosis.

18. Define osmotic pressure.

19. Explain how the number of solute particles in a solution affects its osmotic pressure.

20. Distinguish among solutions that are hypertonic, hypotonic, and isotonic.

21. Define filtration.

22. Explain how filtration moves substances through capillary walls.

23. Explain why active transport is called a physiological process, whereas diffusion is called a physical process.

24. Explain the function of carrier molecules in active transport.

25. Distinguish between pinocytosis and phagocytosis.

26. Describe receptor-mediated endocytosis. How might it be used to deliver drugs across the blood-brain barrier?

27. Explain how transcytosis includes endocytosis and exocytosis.

28. List the phases in the cell cycle. Why is interphase not a time of cellular rest?

29. Name the two processes included in cell division.

30. Describe the major events of mitosis.

31. Explain how the cytoplasm is divided during cell division.

32. Explain what happens during interphase.

33. Define differentiation.

34. Explain how differentiation may reflect repression of DNA information.

35. How does loss of genetic control cause cancer?

chapter objectives

After you have studied this chapter, you should be able to

1. Distinguish between anabolism and catabolism.

2. Explain how enzymes control metabolic processes.

3. Explain how the reactions of cellular respiration release chemical energy.

4. Describe how cells access energy for their activities.

5. Describe the general metabolic pathways of carbohydrate metabolism.

6. Explain how metabolic pathways are regulated.

7. Describe how DNA molecules store genetic information.

8. Explain how protein synthesis relies on genetic information.

9. Describe how DNA molecules are replicated.

10. Explain how genetic information can be altered and how such a change may affect an organism.

Understanding ^Vo rds aer-, air: aerobic respiration— respiratory process that requires oxygen. an-, without: anaerobic respiration—respiratory process that does not require oxygen. ana-, up: anabolism—cellular processes in which smaller molecules are used to build up larger ones. cata-, down: caiabolism—

cellular processes in which larger molecules are broken down into smaller ones. co-, with: coenzyme—substance that unites with a protein to complete the structure of an active enzyme molecule. de-, undoing: deamination—

process by which nitrogen-containing portions of amino acid molecules are removed. mut-, change: muiation—change in the genetic information of a cell. -strat, spread out: subsiraie— substance upon which an enzyme acts. sub-, under: substrate—

substance upon which an enzyme acts. -zym, causing to ferment: enzyme—protein that speeds up a chemical reaction without itself being consumed.

physician and his 17-year-old son ate leftover spaghetti

A with homemade pesto sauce for several days, each time after it had been unrefrigerated for an hour or two. On the fourth day, the food had a peculiar odor, but the father heated it in a pan anyway. About a half hour after lunch, father and son developed severe abdominal pain. The father recovered, but the son began to behave strangely, becoming listless, then very sleepy. A yellow pallor indicated that his liver was malfunctioning.

Because of the rapid onset of abdominal pain after eating reheated food, food poisoning was likely. Indeed, the boy's body fluids and the pan used to reheat the spaghetti contained Bacillus cereus, a type of bacterium that produces a toxin that can cause abdominal pain. In the boy, the toxin took a deadly turn to the liver.

To learn how the bacterial toxin harms the liver, researchers applied toxin from the boy to rat liver cells growing in culture. This experiment revealed that the toxin targets mitochondria, the organelles that house the biochemical reactions that extract energy from nutrients. Specifically, the toxin destroyed the mitochondria's ability to break down fats. Ironically, liver cells have many mitochondria to power the energy-requiring reactions that break down toxins. With his liver mitochondria severely impaired, the boy's liver literally ran out of energy and shut down. He died four days after the spaghetti meal.

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