Small machines

Wording of this Handout:

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How small can a machine get?!?!?!

First of all try to imagine the size of a living cell. Look at your finger. The skin on your finger is made of hundreds of thousands of cells. Now try to imagine being inside just one of those cells. Inside this one cell you will find an engine. It is an engine made of even smaller things called molecules. The engine is called ATPaze. AtPaze is an enzyme which makes something called ATP. Some scientists actually attached tiny blades to the ATPaze engine. It turned like a little fan for two and a half hours. That was the smallest fan in the world.