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| 1. |
List and describe the three categories of membrane proteins and one function for each.
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 2. |
A cell with a 5% concentration of salt in it is placed in a solution with a 15% concentration of salt. Assume that the cell is permeable to water but not to salt. What will happen to this cell? How would you describe the condition of the outside solution?
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 3. |
Why is the plasma membrane referred to as a fluid mosaic model?
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 4. |
Insulin release following a meal triggers cells to transport glucose more rapidly into tissues, causing a decrease in blood glucose levels. Suggest two possible mechanisms for insulin action.
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 5. |
Explain why channel proteins can mediate much more rapid transport than carrier proteins can.
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 6. |
You have discovered a new membrane protein with the following characteristics: it has three regions: Regions A , B, and C. In your study, you notice that region A always faces the extracellular fluid and Region C always faces the cytoplasm. Region B is the part that spans the membrane. Describe the characteristics of Regions A, B, and C. Is this protein most likely a channel protein, carrier protein, or recognition protein?
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 7. |
If you were able to remove all cholesterol from the plasma membrane, what types of changes would you see in membrane characteristics?
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 8. |
Different types of cells have different percentages of proteins in their plasma membranes. For example, neurons contain only 18% proteins, whereas red blood cell membranes contain about 50% proteins. Even higher percentages of protein can be found in membranes of some intracellular organelles; for example, mitochondrial cell membranes contain 76% proteins. Discuss how the difference in composition of these membranes may be related to their function.
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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| 9. |
The bacterium, Vibrio cholerae, produces a protein toxin, cholera toxin. Cholera toxin binds to plasma membrane proteins in the cells of the intestinal lining and causes cells to actively secrete salts and water into the intestinal lumen. This leads to diarrhea and dehydration. The accepted treatment is oral rehydration therapy with dilute salts and glucose. Why does this work?
[Hint]
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
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