Spot the Frippet: enzyme.

 Okay you can't actually point to something and say Look! An enzyme! But then you can't point upwards and say Look! A sky! either, can you, but you still know it's there.

(I'm making the assumption that the sky hasn't fallen where you are, despite the constant predictions of the twenty-four-hour news media.)

Anyway, enzymes. You get them in biological washing powders and dish-washing stuff. They eat dirt if the dirt has come something alive, and you don't even need very hot water for it to work. They're used in meat tenderisers, too. They're wonderful things, enzymes, and that's even before you consider that they are keeping you alive.

Yes, you contain thousands of enzymes, and if even one of them is missing or a bit dodgy then it can cause really serious problems. You need enzymes to operate at every level. Every living cell in your body relies on them to send signals. They help your muscles contract and your gut digest food. Sometimes missing enzymes can be replaced: for instance, someone lactose intolerant can take some tablets containing the lactase enzyme and, hey presto!

Without enzymes there'd be no naturally-occurring alcohol. Fireflies wouldn't shine. Cows couldn't eat grass. There's be no cheese, biscuits, clear fruit juice - and your contact lenses would be really itchy and dirty.

Let's make today a day to appreciate them.

Illustration: crystal structure of bovine chymotripsin by Mattyjenjen

Spot the Frippet: enzymes. This word was coined by Wilhelm Kühne. He got the word from the Greek enzumos, which means risen (as in bread).