A、The impact of enzymes on chemical reactions. B、The way the body produces enzymes. C、The structure of enzymes. D、Types of chemi

Let’ s begin today by discussing enzymes. Enzymes are what make many of the body’ s biochemical reactions possible. Actually biochemical reactions can take place without them, but at much lower rates. In fact an enzyme may cause a reaction to proceed billions of times faster than it would otherwise. Before I go on to the biochemical specifics of how this works, let me provide a figurative example. I think it will help illustrate the power of enzymes more clearly. Now, suppose you got a bag and you put a bunch of locks in it, just small padlocks. Then you put in all the keys that go with the locks. And you closed the bag and shook it hard. No matter how long you shook, chances are very small that any key would get inserted in any of the locks. But if you took them all out of the bag and this time used your hands to insert the keys in the locks, you could combine them much easier.
    Q22: What is the passage mainly about?
    Q23: Why does the professor talk about locks and keys?
    Q24: What are enzymes?