Biology Virus Essay

Topics: Virus, Bacteria, DNA Pages: 2 (630 words) Published: January 3, 2012
Virus Essay

A virus is a microorganism that cannot reproduce without a host. As a result of this, there has been a lot of controversy on whether or not a virus is a living or non-living organism. The definition for life is, “the condition that distinguishes organisms from inorganic objects and dead organisms, being manifested by growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally.” Viruses have characteristics of both living and non-living organisms, for example, a living characteristic includes reproduction. A non-living characteristic of a virus is that they cannot have both DNA and RNA. The living characteristics of viruses state that viruses can reproduce, but viruses can only reproduce with the help of a host. As a result of viruses not being able to replicate on their own, viruses are not living organisms.

Viruses are small infectious particles that have nucleic acid. They can come in many different shapes and sizes. Although viruses vary in shape the common virus has four main parts, the head, DNA or RNA, tail sheath, and tail fiber. The head of a virus is a protein shell that protects the DNA inside it also known as the genome. In comparison, viruses and living organisms both are made up of smaller units that form up to make something larger. The physical appearance of a virus and living organisms are different and what a virus is made up of is different in comparison to a living organism.

Viruses are made up of proteins and nucleic acid. The protein comes together to form an encasing shell for the nucleic acid. The protein shell is called a capsid. The nucleic acid inside a capsid can either be DNA or RNA, but never both. Viruses can be classified depending on the features they have, for example the various shapes of a capsid can determine the type of virus. A capsid can be a simple or complex structure. The most complex capsid is found...
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