Compare and contrast the pathogenicity of Clostridium botulinum and Clostridium tetani, including mechanisms of action of their toxins and disease manifestations.
What will be an ideal response?
Both bacteria are anaerobic, endospore-formers that produce neurotoxins. Disease results when the endospores are introduced deep into the tissues. Both neurotoxins interfere with motor control.
Botulism toxin, produced by C. botulinum, binds the cytoplasmic membranes of motor neurons at the synapse and prevents the release of acetylcholine neurotransmitter and, consequently, prevents signaling to muscle cells. When muscle cells do not receive signals from motor neurons, they remain relaxed, resulting in a flaccid paralysis. Lack of motor control produces a long list of symptoms, the most serious of which is respiratory failure, because respiratory muscles can be affected by botulism toxin.
Tetanus toxin, produced by C. tetani, targets inhibitory neurons, which release neurotransmitters that prevents muscle cells from responding to acetylcholine stimulation to contract. Under normal circumstances, when one muscle of an antagonistic pair is stimulated to contract, the other muscle is inhibited from contracting, allowing for normal movement by alternate flexion and extension. When tetanus toxin blocks the release of inhibitory neurotransmitter, both muscles of the antagonistic pair contract spasmodically and sometimes lock in continuous contraction, resulting in nonflaccid paralysis. Loss of control of the respiratory muscles can lead to respiratory failure. Tetanus toxin can also interfere with autonomic (involuntary) muscle control, which may result in irregular heartbeat and possibly heart failure.
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Could an isolated melanin granule move along an actin microfilament?
A. Yes, melanin granules have motor proteins. B. Yes, motor proteins all use ATP to cause a conformation change. C. No, motor proteins are specific for the type of filament they bind. D. Answers a and b are both correct.
You ask the butcher to grind a sirloin roast to be used for hamburger. You family likes hamburgers rare, so you undercook the meat. Unfortunately, within 2 days they develop the symptoms of gastrointestinal disease: diarrhea, bloating, and vomiting. Which of the following statements best describes what happened?
A. The meat grinder was contaminated, and bacteria were transferred and distributed throughout the meat. B. The meat became contaminated by bacteria from other foods in your refrigerator. C. The meat became contaminated by bacteria on the barbeque grill, coating both sides of the hamburger patties. D. The animal was sick before slaughter, and the sirloin was contaminated.
During an oxidation reaction,
a. the donor molecule gains an electron and becomes oxidized. b. the acceptor molecule loses an electron and becomes oxidized. c. the donor molecule loses an electron and becomes oxidized. d. the acceptor molecule gains an electron and becomes oxidized.