What is a Virus?

Papillomavirus Credit: 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 a virus to find out.

A virus particle, also known as a virion, is essentially nucleic acid (DNA or RNA) enclosed in a protein shell or coat. Viruses may have double-stranded DNA, double-stranded RNA, single-stranded DNA or single-stranded RNA.

The protein coat that envelopes the genetic material is known as a capsid. Some viruses may also have a membrane-like envelope around the capsid or a protein tail attached to the capsid.

Learn more about viruses:

• Virus Replication
  
• Virus Quiz