Bacteria Made Simple
Our world contains many organisms and things
on-the-edge of life. They range in sizes so small that a light
microscope cannot see them to organisms larger than an elephant.
Bacteria and viruses are two examples of these very small earth
inhabitants. Both are related in that both can cause sickness, and they
both have genetic material. These two things differ in a few important
Viruses are much smaller than bacteria. Bacteria
can be seen under a light microscope when stained with special stains.
Until the electron microscope was invented, viruses could not be seen at
all. An electron microscope can magnify objects up to 10,000,000 times,
which enables scientists to see objects that are beyond tiny.
Bacteria are a living organism, while viruses are
not. Last week, we reviewed the characteristics needed for something to
be considered alive. These characteristics include cells, reproduction,
and metabolism. Bacteria are single-celled organisms that reproduce
through a process called binary fission--the bacteria cell splits into
two identical cells. Viruses are not made of cells, but consist of a
core of genetic material surrounded by a protein shell.
Unlike most bacteria, viruses are not complete
cells that can function on their own. A single virus particle in itself
is essentially inert. It lacks the general components needed to
reproduce. It must first infect a host cell, and then the host cell
reproduces with the virus inside. Viruses cannot convert carbohydrates
to energy, the way other living cells do. Viruses depend on other
organisms for energy.
There are thousands of different viruses, and they
can cause a wide range of disease. In humans, for instance, rhinoviruses
cause colds, influenza viruses cause the flu, and herpes viruses cause
cold sores and chicken pox among other things. Viruses can cause a range
of conditions--from colds to measles to AIDS.
Most viruses do not cause serious disease and are
killed by the body’s immune system. In many cases, you may never even
know you had a virus. Unlike bacteria, which can be killed by
antibiotics (how will be seen next week), most viruses are not effected
by existing medicines. On a good note, scientists have been able to
develop vaccines to combat against certain viruses. Many medicines can
help alleviate the symptoms of a viral infection. Cough syrup is one
There are many differences between viruses and
bacteria. Many of these differences stem from the fact that viruses are
not a living thing, while bacteria are. Both cause sickness. Viruses
cannot usually be treated, but the symptoms can. Bacteria can be treated
with antibiotics. Next week, we will look at how antibiotics work.