10. Cell Signaling

Classes of Signaling Receptors

Multiple Choice
Domoic acid is a neurotoxin produced by some species of alga. Domoic acid binds to the kainate receptor on neurons in parts of the brain. The kainate receptor facilitates the movement of calcium into the cell. Excess domoic acid–induced stimulation of the neural kainate receptors causes neural damage and short-term memory loss. Based on this, which of the following is likely true?
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Multiple Choice
A G protein is active when __________.
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Multiple Choice
If a modified form of GTP that cannot be enzymatically converted to GDP were added to a culture of cells, the likely result would be __________.
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Multiple Choice
What event would activate a G protein?
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Multiple Choice
Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. Which of the following changes to Ras could explain uncontrolled division in a cancer cell that has mutated Ras present?
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Multiple Choice
Cholera develops when the bacterial toxin __________.
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Textbook Question
Lipid-soluble signaling molecules, such as aldosterone, cross the membranes of all cells but affect only target cells because
a. Only target cells retain the appropriate DNA segments.
b. Intracellular receptors are present only in target cells.
c. Only target cells have enzymes that break down aldosterone.
d. Only in target cells is aldosterone able to initiate the phosphorylation cascade that turns genes on.
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Textbook Question
Summarize the experimental evidence in sponges showing that animal cells adhere to each other selectively. Explain the molecular basis of selective adhesion.
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Textbook Question
Suppose you have an antibody that binds to the receptor tyrosine kinase illustrated in Figure 11.16. When you add this antibody to the cell, you find that it activates the cell response, even when no signaling molecule is present. Explain this result.
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