Saturday, December 1, 2007

Concept 27.5

I. Contrast exotoxins and endotoxins.

a) Exotoxins: can produce disease even if the prokaryotes that manufacture them are not present. Endotoxins: released only when the bacteria die and ther cell walls break down.

b) Exotoxins: proteins secreted by prokaryotes. Endotoxins: lipopolysaccharides released from the outer membrane of gramnegative bacteria that have died.

II. What features of prokaryotes make them a potential bioterrorism threat?

a) Pathogenic prokaryotes pose a potential threat as weapons of bioterrorism. For example, Bacillus anthracis, the bacterium that causes anthrax, were found in envelopes mailed to members of news media and the U.S. Senate. Another candidate of prokaryote that could be used as weapons is the C. botulinum & Yersinia pestis, which causes plague.
b) Their quick reproduction can make it difficult to combat them with antibiotics, particularly as they may evolve resistance to the drugs. Some also have the ability to form endospores and withstand harsh environments, surviving until conditions become more favorable.

III. Identify at least 2 ways that prokaryotes have affected you positively today.

a) eating fermented foods such as yogurt and cheese; having clean water and prokaryote-produced medicines

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