26.1 A virus consists of a nucleic acid surrounded by a protein coat

The Discovery of Viruses: Scientific Inquiry
In 1935, Wendell Stanley confirmed this hypothesis by crystallizing the infectious particle, now known as tobacco mosaic virus (TMV) 菸草嵌紋病

Structure of Viruses
Viruses are not cells

Viruses are very small infectious particles consisting of nucleic acid enclosed in a protein coat and, in some cases, a membranous envelope 封套

Viral Genomes
Viral genomes may consist of either

i. Double- or single-stranded DNA

ii. Double- or single-stranded RNA

Depending on its type of nucleic acid, a virus is called a DNA virus or an RNA virus

Capsids and Envelopes
A capsid 衣殼 is the protein shell that encloses the viral genome

Capsids are built from protein subunits called capsomeres 殼粒

These viral envelopes 病毒封套 surround the capsids of influenza viruses and many other viruses found in animals

Bacteriophages 噬菌體, also called phages, are viruses that infect bacteria