Country: United States
Date: September 2005
Why Do antibiotics kill bacteria and not US?
Antibiotics ideally are designed to attack something in the cellular
machinery that bacteria have the humans do not. For instance, penicillin
interrupts the building of the bacterial cell wall and human cells do not
have cell walls. Unfortunately, many antibiotics can be somewhat difficult
to take because they end up affecting something in our body like the good
bacteria in our intestine. This is just one of the reasons to use
Great question! Usually, they are directed against a structure of process
that bacteria or fungi have that we don't. For example, bacteria have a
characteristic cell wall that humans don't have (humans don't have cell
walls at all!). Penicillin disrupts cell wall synthesis and causes bacterial
cells to burst.
Penecillin, for example, inhibits cell wall synthesis in gram negative
bacteria, but since humans don't have a cell wall in is harmless to us,
unless you are allergic to it. Streptomycin and its' derivatives bind to
bacterial ribosomes and inhibit protein synthesis, but since streptomycin
doesn't bind to human ribosomes, again it is harmless to us.
Ron Baker, Ph.D.
Vitamin C (ascorbic acid) is an example of a water soluble anti-oxidant. It
reacts with free radicals like atomic oxygen thus stopping the free raical
with reacting with DNA and proteins which could damamge your cells. An
example of a fat soluble anti-oxidant is Vitamin E. By definition, it is
insoluble in water.
Ron Baker, Ph.D.
Antibiotics target differences between bacterial cells and our cells. For
example, a bacterial cell may have a protein with a slightly different shape
than the same protein in our cells. If an antibiotic binds specifically to a
unique "bump" that is found on the bacterial protein, but not found on the
human version, then it may kill the bacterial cell by inactivating the
protein. Our protein, which does not have the same shape, will not be bound
by the antibiotic, and hence, not affected. It's all about exploiting minor
differences between bacterial cells and human cells.
Paul Mahoney, PhD
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Update: June 2012