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Chapter 6. Biotransformation of Xenobiotics

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Xenobiotic biotransformation is performed by multiple enzymes in multiple subcellular locations. Where would one of these enzymes most likely NOT be located?

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a. cytosol.

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b. Golgi apparatus.

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c. lysosome.

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d. mitochondria.

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e. microsome.

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All of the following statements regarding hydrolysis, reduction, and oxidation biotransformations are true EXCEPT:

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a. The xenobiotic can be hydrolyzed.

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b. The xenobiotic can be reduced.

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c. There is a large increase in hydrophilicity.

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d. The reactions introduce a functional group to the molecule.

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e. The xenobiotic can be oxidized.

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Which of the following is often conjugated to xenobiotics during phase II biotransformations?

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a. alcohol group.

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b. sulfhydryl group.

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c. sulfate group.

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d. aldehyde group.

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e. carbonyl group.

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Which of the following is a true statement about the biotransformation of ethanol?

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a. Alcohol dehydrogenase is only present in the liver.

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b. Ethanol is reduced to acetaldehyde by alcohol dehydrogenase.

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c. Ethanol and hydrogen peroxide combine to form acetaldehyde with the aid of catalase.

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d. In spite of its catalytic versatility, cytochrome P450 does not aid in ethanol oxidation.

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e. Acetaldehyde is oxidized to acetic acid in the mitochondria by aldehyde dehydrogenase.

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Which of the following enzymes is responsible for the biotransformation and elimination of serotonin?

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a. cytochrome P450.

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b. monoamine oxidase.

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c. flavin monooxygenase.

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d. xanthine oxidase.

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e. paraoxonase.

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Which of the following reactions would likely NOT be catalyzed by cytochrome P450?

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a. dehydrogenation.

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b. oxidative group transfer.

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c. epoxidation.

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d. reductive dehalogenation.

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e. ester cleavage.

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All of the following statements regarding cytochrome P450 are true EXCEPT:

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a. Poor metabolism or biotransformation of xenobiotics is often ...

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