A patient was admitted to the emergency department suffering from severe diarrhea that had lasted a couple of days. There had already been significant weight loss. On examination, his stool was very watery with white bits of mucus and little odor. What pathogen is likely causing this condition, and how does it cause disease?
What will be an ideal response?
The patient is suffering from cholera, and the causative agent is Vibrio cholerae. The most important virulence factor of this pathogen is an exotoxin called the cholera toxin, which is made of five identical B subunits and one A subunit. These subunits attach to epithelial cells in the intestine and eventually lead to the production of cyclic AMP (cAMP). In turn, the cAMP stimulates the active secretion of excess electrolytes into the lumen, which in turn causes water to leave the tissues, diluting the intestinal contents and leading to severe dehydration.
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In humans, what gene determines maleness?
A. DSX B. sex-1 C. SRY D. SXL
The term "junk DNA" is no longer used because these regions of DNA have been found to be associated with all of the following except
A) miRNAs. B) speciation. C) binding sites for regulatory regions. D) All of the above have been associated with "junk DNA." E) None of the above have been associated with "junk DNA."
Of the stages of translation, which one is basically the same in both eukaryotes and prokaryotes?
a. initiation b. termination c. translation d. elongation
Photosynthetic organisms using the oxygenreleasing
pathway appeared on earth about ____ billion years ago.
a. 1.3 b. 1.8 c. 2.3 d. 2.7 e. 3.8