Transcript

HOST:

Many of us already know that infectious illnesses are often caused by viruses or bacteria. But how many of us know actually what a difference that makes?

You'd normally need a microscope to explore the difference between viruses and bacteria. But studying things in a lab is not really my scene. I find it easier to explain stuff when I can get my hands dirty and see things properly. That's why I've come here.

The most obvious difference between viruses and bacteria is size. To us, a single bacterium might be pretty small, maybe a thousandth of a millimetre. But to a virus, they're looking fairly large. If we scale things up and took a typical virus to be the size of a suitcase, in which case a bacterium would be the size of a van.

[HORN HONKS TWICE]

And the comparison doesn't end there. Just like this van is a fully functioning machine with different working parts for specific jobs-- like wheels, engine, fuel pump, windscreen, etc. so too is a bacterium. It's a self-contained unit with a wall around it and all the biological machinery of a living cell.

Whereas a virus just has a thin protein coat, inside it's practically empty-- no machinery of its own, just a string of genetic material, like DNA. Like, in fact, an instruction manual. Alone, it can do nothing. It has to hijack a living cell and turn it to its own purposes.

It's only by using something else's biological machinery that a virus can repeatedly clone itself before bursting out and infecting countless more cells in a destructive chain reaction.