by Virginia Gaces

Created on: December 03, 2008   Last Updated: January 17, 2009

The morphological appearance of a virus is so beautiful that you would not expect this seemingly harmless and visually attractive entity to be a deadly, virulent microorganism.

This minute organism, first discovered by Dmitri Iwanowski in 1892, is a universal microbe present in a variety of hosts, including us - the Homo sapiens. Contrary to common knowledge; however, not all viruses are disease causing, some of them also have beneficial effects on their hosts.

So what is the anatomy of a virus? What is its bodily structure?

1. Viruses have a size ranging from 10 to 300 nm (nanometers).

The largest is the Ebola virus which is, more or less, 1 um (micrometer) in length. To help you visualize its size, 1 inch is 25399999.999999996 nm; and 1 inch in micrometers is 25400.

They can only be seen under an electron microscope which usually utilizes unstained preparations of viruses under a dark background.

2. A virus is composed of either a DNA or RNA, but not both.

This DNA or RNA is the type of the nucleic acid genome present in all viruses. Viruses depend on their host's ribosomal synthesis because they could not synthesize their own ribosomes; this property makes them unique from all other organisms.

Living cells are composed of both RNA plus a DNA, which multiply through binary fission, mitosis or meiosis, while viruses cannot replicate on their own, they need a host to be able to do this.

3. A virus is surrounded by a capsid.

This is a protein coat made up of several protein units called capsomeres. This maybe helical (coiled tubes), spherical, polyhedral (various sides), enveloped, or a combination of any of these shapes. That is why they look captivating under the microscope.

4. Some viruses have outer coverings made up of lipids and polysaccharides.

These are also called enveloped viruses. Lipids are commonly called fats, and polysaccharides are complex carbohydrates.

5. Some may have sheaths, tails or tail fibers.

These are usually found in bacterial viruses.

6. They have a core protein.

This protein comprises the interior of the virus could interact with the cytoplasm of the host cell where the virus may alter them and produce toxins and become harmful, or remain harmless and exercises no detrimental effect.

The anatomy of a virus therefore is one of great variety and interest. It can be influenced entirely by the host's specific biochemical characteristics or cellular components.

References:

Burton, Gwendolyn et al, Microbiology for the Health Sciences: Lippincot Williams, 2004

Dimmock, N.J, et al, Introduction to Modern Virology: Blackwell Publishing, 2007

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