NAME IT Use the key in the Clinical Focus box to identify the gram-negative, oxidase-positive rod causing pneumonia in a sea otter. It is H₂S-positive, indole-negative, and urease-positive.

Bacteria use the enzyme urease to obtain nitrogen in a form they can use from urea in the following reaction:

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What purpose does the enzyme serve in this reaction? What type of reaction is this?

Define and explain the importance of each of the following:

a. catalase

b. hydrogen peroxide

c. peroxidase

d. superoxide radical

e. superoxide dismutase

An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an

a. aerobe.

b. aerotolerant anaerobe.

c. obligate anaerobe.

Suppose you inoculate three flasks of minimal salts broth with E. coli. Flask A contains

glucose. Flask B contains glucose and lactose. Flask C contains lactose. After a few hours of incubation, you test the flasks for the presence of ß-galactosidase. Which flask(s) do you predict will have this enzyme?

a. A

b. B

c. C

d. A and B

e. B and C

The _______________________ test detects if an organism can convert hydrogen peroxide to water and oxygen. The test result is usually _______________________ in anaerobic microbes and usually _______________________ in aerobic microbes. You know the test is positive by _______________________.

Which of the following does not affect the function of enzymes?

a. ubiquinone

b. substrate concentration

c. temperature

d. competitive inhibitors

Which of the following statements best describes ribozymes?

a. Ribozymes are proteins that aid in the production of ribosomes.

b. Ribozymes are nucleic acids that produce ribose sugars.

c. Ribozymes store enzymes in ribosomes.

d. Ribozymes process RNA molecules in eukaryotes.

How does amination differ from transamination?