CHAPTER 6: Biotransformation of Xenobiotics

Chapter 6. Biotransformation of Xenobiotics

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

a. cytosol.

b. Golgi apparatus.

c. lysosome.

d. mitochondria.

e. microsome.

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

a. The xenobiotic can be hydrolyzed.

b. The xenobiotic can be reduced.

c. There is a large increase in hydrophilicity.

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

e. The xenobiotic can be oxidized.

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

a. alcohol group.

b. sulfhydryl group.

c. sulfate group.

d. aldehyde group.

e. carbonyl group.

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

a. Alcohol dehydrogenase is only present in the liver.

b. Ethanol is reduced to acetaldehyde by alcohol dehydrogenase.

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

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

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

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

a. cytochrome P450.

b. monoamine oxidase.

c. flavin monooxygenase.

d. xanthine oxidase.

e. paraoxonase.

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

a. dehydrogenation.

b. oxidative group transfer.

c. epoxidation.

d. reductive dehalogenation.

e. ester cleavage.

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

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