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Critical Thinking

MicrobiologyCritical Thinking

Critical Thinking


Suppose you were screening produce in a grocery store for the presence of E. coli contamination. Would it be better to use a polyclonal anti-E. coli antiserum or a mAb against an E. coli membrane protein? Explain.


Both IgM and IgG antibodies can be used in precipitation reactions. However, one of these immunoglobulin classes will form precipitates at much lower concentrations than the other. Which class is this, and why is it so much more efficient in this regard?


When shortages of donated blood occur, O-negative blood may be given to patients, even if they have a different blood type. Why is this the case? If O-negative blood supplies were depleted, what would be the next-best choice for a patient with a different blood type in critical need of a transfusion? Explain your answers.


Label the primary and secondary antibodies, and discuss why the production of end product will be proportional to the amount of antigen.

Ys are attached to a surface. The space between the Ys is covered in a black layer. A circle is attached to each Y. Another Y with a large purple circle is attached to each of the smaller circles which are attached to the Ys attached to the surface.

A patient suspected of having syphilis is tested using both the VDRL test and IFA. The IFA test comes back positive, but the VDRL test is negative. What is the most likely reason for these results?


A clinician suspects that a patient with pneumonia may be infected by Legionella pneumophila. Briefly describe two reasons why a DFA test might be better for detecting this pathogen than standard bacteriology techniques.

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