How it works
An unlabeled virus diagram in three drawings on one sheet: a round enveloped virus cut in half, and under it a rod-shaped capsid and a many-sided one. Seven names are left off, one for each label line.
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The seven names, from the outside in
On the round virus: spike proteins, envelope, capsid, capsomeres, genetic material. On the two small drawings: helical virus for the rod, icosahedral virus for the ball of flat faces.
Capsid or capsomere
Both names sit on the same six-sided shell. The capsid is the whole shell, and its line ends just inside the beads. A capsomere is one of the round beads the shell is built from, so its line ends on a single bead. The coil in the middle is the genetic material, the ring outside the shell is the envelope, and the knobbed stalks on the ring are the spike proteins.
- The wavy strand through the rod is genetic material too. Only the coil in the round virus is asked.
- The lines across the ball mark its flat triangular faces. They take no name.
- A class sheet may say nucleic acid or genome for genetic material, and protein coat for capsid.
Questions and answers
Is a virus a cell?
No. A virus has no cellular structure. Outside a host it is a particle of genetic material in a protein coat, and it can multiply only inside a living cell.
Do all viruses have an envelope?
No. Every virus has genetic material and a capsid, and only some have an envelope outside it. The rod and the ball at the bottom of the sheet are drawn without one.
What is a nucleocapsid?
The capsid together with the genetic material it holds. On the sheet that is the six-sided shell and the coil inside it. The envelope and the spike proteins are not part of it.
Can you see a virus with a light microscope?
Mostly not. Most viruses are too small for an optical microscope and are pictured with electron microscopes. A virus diagram is therefore a scheme of the parts, not a drawing made from a slide.