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Unformatted text preview: ticide become immune to it.” This is incorrect. The
presence of the pesticide selects for flies that are most able to metabolize the toxin. Most of the flies die.
The resistant survivors produce offspring, which may inherit the genes for resistance. This is an example of
natural selection, not of immunity. Notes Biology 103
Dr. Karen Bledsoe
http://www.wou.edu/~bledsoek/ • The words “antibody” and “antibiotic” are often confused. An antibiotic is a medicine we take that consists of
a substance that is toxic to bacteria but not to humans. These are often derived from soil microbes that use
these chemicals to battle one another for territory. An antibody is a protein produced by our own immune
system that tags and may disable invading bacteria. Taking antibiotics does not interfere with our ability to
produce antibodies. Antibiotics do not make us “less immune” to diseases, nor do they weaken our
• “Antigen” is another term that confuses students, who often mix up “antibody” and “antigen,” or believe that
the immune system produces antigens. An antigen is a protein that causes an immune response. For
example, proteins on the surface of an invading bacteria are antigens.
• Many students think that “antibiotic resistance” is something our own bodies do: that if we take antibiotics
too long, our bodies are somehow “desensitized” to them or “become immune” to their effects. Since we do
become desensitized to psychoactive and addictive drugs, it is easy to see where this idea would come
from. In fact, it is not people who become resistant to antibiotics; it is the bacteria themselves. Different
individual bacteria have different abilities to resist the effects of an antibiotic or to metabolize the antibiotic. If
we take an antibiotic for too short a period of time, some bacteria may survive. Those that do will most likely
be the most re...
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This document was uploaded on 02/25/2014 for the course BIOLOGY 103 at Western Oregon University.
- Winter '09