How it works
A virus diagram labeled: an enveloped virus cut in half, then the two simple shapes a capsid can take. Start with the 5 parts of a virus.
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Inside out
In the middle is the genetic material, DNA or RNA. Round it is the capsid, a protein coat built from many capsomeres. Some viruses also have an envelope of lipid membrane, studded with spike proteins.
Capsid shapes
The simplest capsids are helical, a rod with the capsomeres wound round the genetic material, or icosahedral, a many-sided ball. Others, like the bacteriophage, are more complex.
- An envelope is fragile: soap, heat and drying break it easily, so enveloped viruses do not last long outside a host.
Questions and answers
What are the parts of a virus?
Every virus has genetic material (DNA or RNA) and a protein coat called the capsid. Some also have an outer envelope of lipid membrane, often with spike proteins sticking out.
What is a capsid made of?
Protein subunits called capsomeres, which fit together to form a helical rod, an icosahedral ball or a more complex shape.
Where does a virus envelope come from?
From the membrane of the host cell the virus came out of, with the virus's own proteins, such as spike proteins, built into it.