1. Education
Send to a Friend via Email

Viruses

By

1 of 2

Viruses
Adenovirus

Adenovirus

Images courtesy of Linda M. Stannard, University of Cape Town.
Scientists have long sought to uncover the structure and function of viruses. Viruses are unique in that they have been classified as both living and nonliving at various points in the history of biology. What makes them so interesting? Let's look at the structure of viruses.

Viruses: Structure

A virus particle, also known as a virion, is essentially a nucleic acid (DNA or RNA) enclosed in a protein shell or coat. Viruses are extremely small, approximately 15 - 25 nanometers in diameter.

Viruses: Genetic Material

Viruses may have double-stranded DNA, double-stranded RNA, single-stranded DNA or single-stranded RNA. The type of genetic material found in a particular virus depends on the nature and function of the specific virus. The genetic material is not typically exposed but covered by a protein coat.

The viral genome can consist of a very small number of genes or up to hundreds of genes depending on the type of virus. Note that the genome is typically organized as a long molecule that is usually straight or circular.

©2014 About.com. All rights reserved.