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The Difference Between Bacteria, Viruses, and Toxins Bacteria
Bacteria
are unicellular organisms. They vary in shape and size from spherical
cells (cocci) to long rod-shaped organisms (bacilli).
The shape of the bacterial cell is determined by the rigid cell
wall. The interior of the cell contains the nuclear material (DNA),
cytoplasm, and cell membrane that are necessary for the life of the
bacterium. Under special
circumstances some types of bacteria can transform into spores. The
spore of the bacterial cell is more resistant to cold, heat, drying,
chemicals and radiation than the vegetative bacterium itself. Spores are
a dormant form of the bacterium and, like the seeds of plants; they can
germinate when conditions are favorable.
Bacteria generally cause disease in human beings and animals by
one of two mechanisms: by invading host tissues and/or by producing
poisons (toxins). Many
pathogenic bacteria utilize both mechanisms. Viruses Viruses are the simplest microorganisms and consist of a nucleocapsid protein coat containing genetic material, either RNA or DNA. In some cases, an outer lipid layer also surrounds the viral particle. Viruses are much smaller than bacteria. Viruses are intracellular parasites and lack a system for their own metabolism; therefore, they are dependent on the synthetic machinery of their host cells. This means that viruses, unlike the bacteria, require living cells in order to multiply. The host cells can be from humans, animals, plants, or bacteria. Every virus requires its own special type of host cell for multiplication, because a complicated interaction occurs between the cell and virus. A virus typically brings about changes in the host cell that eventually lead to cell death. Toxins Toxins are harmful substances produced by living organisms (animals, plants, microbes). Features that distinguish them from chemical agents, such as VX, cyanide, or mustard, include being not man-made, non-volatile (no vapor hazard), usually not dermally active (mycotoxins are the exception), and generally much more toxic per weight than chemical agents. Their lack of volatility is very important and makes them unlikely to produce either secondary or person-to-person exposures, or a persistent environmental hazard.
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Emergency Preparedness & Response Section |
Copyright © 2005 North Dakota Department of Health |