Microorganisms and Disease
Mucus helps in protecting against pathogens by

lowering the pH
sequestering Iron
blocking access and attachment of pathogens to mucosal surfaces
facilitating the growth of normal flora

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Microorganisms and Disease
The "A" subunit of diphtheria toxin

binds host cell receptors found on heart cells
cause ADP ribosylation of a factor involved in protein synthesis
forms cAMP that leads to fluid accumulation
lysis macrophages with the release of cytokines

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Microorganisms and Disease
Which of the following is common in the disease caused by Coryne-bacterium diphtheriae and Bacillus anthracis?

Both organisms cause skin and respiratory tract infections
The most serious disease symptoms are the direct result of toxin action
Both organisms are gram-positive spore formers
Diphtheria toxin and edema toxin are ADP ribosylating toxins

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Microorganisms and Disease
Cholera toxin is an A-B type toxin in which the B portions bind to a receptor on a host cell and the A portion enters the cell to cause

ADP ribosylation of a G protein that locks it into an active form that stimulates adenylate cyclase to make cAMP
ADP ribosylation of guanylate cyclase that stimulates production of cGMP
cleavage of rRNA that results in disruption of ribosome function
ADP ribosylation of adenylate cyclase that stops production of cAMP

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