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Chapter 2. Cell Structure

A 22-year-old man presents with a painless 1-cm ulcer on the shaft of his penis. Inguinal lymphadenopathy is present. The patient admits trading drugs for sex and has several sexual partners. An RPR test result is positive, and syphilis is suspected; however, a Gram-stain of a swab specimen from the ulcer shows no bacteria. T. pallidum, the causative agent of syphilis, cannot be visualized by light microscopy because

(A) It is transparent.

(B) It cannot be stained by ordinary stains.

(C) It has a diameter of less than 0.2 µm.

(D) The wavelength of white light is too long.

(E) Rapid movement of the organism prevents visualization.

Chloramphenicol, an antibiotic that inhibits bacterial protein synthesis, will also affect which of the following eukaryotic organelles?

(A) Mitochondria

(B) Golgi complex

(C) Microtubules

(D) Endoplasmic reticulum

(E) Nuclear membrane

Which of the following structures is not part of the bacterial cell envelope?

(A) Peptidoglycan

(B) Lipopolysaccharide

(C) Capsule

(D) Gas vacuole

(E) S-layer

A group of teenagers became ill with nausea, vomiting, severe abdominal cramps, and diarrhea after eating undercooked hamburgers from a local restaurant. Two of the teenagers were hospitalized with hemolytic-uremic syndrome. E. coli O157:H7 was isolated from the patient’s stools as well as from uncooked hamburgers. The O157 refers to which bacterial structure?

(A) Lipopolysaccharide

(B) Capsule

(C) Flagella

(D) Fimbriae

(E) S-layer

Which of the following components is present in Gram-negative bacteria but not in Gram-positive bacteria?

(A) Peptidoglycan

(B) Lipid A

(C) Capsule

(D) Flagella

(E) Pili

Group A streptococci are the most common bacterial cause of pharyngitis in school-age children 5–15 years of age. The most important cell ...

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