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Are Bacteria And Virus Different?
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Very often, when we are
down with a fever, with some attending discomfort, we are told that
we have a virus fever or a virus infection. Are bacteria and viruses
the same, or are they different? We have a general tendency to
confuse bacteria and viruses, simply because we connect both the
terms with disease.
As it happens, the two
are different from each other. A small interesting fact is that a
virus can grow inside a bacterium. Viruses attack and cause
infections and diseases when under certain circumstances, whereas
not all bacteria are harmful. There are at least two thousand
species of bacteria and most of them are harmless, while many of
them are helpful too. |
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Anton van
Leeuwenhoek, a part-time janitor working in Delft, Holland,
using a microscope that he built himself, discovered bacteria.
It is said that he was observing through his microscope a tiny
raindrop that had remained in a tub for quite a while, when he
noticed that there were plenty of “tiny animals” (what we now
call protozoa) swimming in the water. He said that he also saw
equally small-sized animals (what we call bacteria now) that did
not move at all. The janitor’s claims were later, presented,
verified and he was eventually made a Fellow of the Royal
Society in 1680.
Bacteria is present
everywhere. Some live in the mouths, noses and intestines of
animals and human beings. Others live on fallen leaves, dead
trees, animal wastes, in fresh water and salt water, in milk and
in most foods. A single drop of sour milk may contain a hundred
million bacteria, but basically a bacterium contains only a
single cell. |
Bacteria on the surface of tooth |
Science has not decided
whether to classify bacteria under animals or plants, since they
have some features of both plants and animals. Most bacteria
reproduce by fission, where the cell divides into two.
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Viruses are very
small organisms. They are so tiny that they can be seen in
detail only under an electron microscope. Viruses grow and
multiply only when they are inside living cells. They are
incapable of growing unless they are inside the cells of
animals, plants or bacteria. Outside living cells, they do not
change in any way and may even appear lifeless.
There are different
types of viruses. Those that attack bacteria are called
bacterial viruses, those harmful to plants are known as plant
viruses and viruses that attack plants are called plant viruses. |
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Viruses attached to inside of cell |
The viruses that infect
human beings and animals may be breathed in or swallowed or they may
enter through an opening in the skin. Some of them destroy cells by
growing inside the cells, others cause the membranes separating two
cells to dissolve and still others cause cells to become malignant.
Here’s a little known
fact about one strain of the virus herpes simplex. Why are we
talking only about this virus? For the simple reason that it is the
only virus that lives inside the nerve fibers of ninety per cent of
adults. It is usually dormant, but when the host human is of poor
health, the virus can erupt on the lips as cold sores. |
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