- To look at infected cells
and some of the contents of infected cells,
we can use normal light microscopes
that you're familiar with,
that you may have in your classroom.
Some of the things that we need to see,
some of the virus machinery,
the infectious virus particle themselves,
these are actually smaller than a light microscope can see.
They're just at the molecular scale,
not the cellular or subcellular scale,
and to visualize those sorts of objects,
we need to use not a light microscope,
but an electron microscope.
To visualize the scales of these things,
you might think about a millimeter.
A useful unit for the size of cells would be a micrometer.
That would be a thousand times smaller than a millimeter.
And then if we want to talk about a molecular scale,
a more useful unit would be a nanometer.
That's a thousand times smaller than a micrometer.
That's the scale we're looking at,
on the order of a million times smaller than a millimeter,
or even smaller than that.