The Function of Enzymes

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  • 0:01 What is an Enzyme?
  • 0:41 Lowering Activation Energy
  • 1:18 Enzymes at Work
  • 1:53 Temperature,…
  • 3:25 Lesson Summary
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Lesson Transcript
Instructor: Kevin Newton

Kevin has edited encyclopedias, taught history, and has an MA in Islamic law/finance. He has since founded his own financial advice firm, Newton Analytical.

Have you ever used a drill to accelerate building something that only requires a screwdriver? It went a lot faster, didn't it? In this lesson, you'll learn how that drill is a lot like an enzyme.

What Is an Enzyme?

Have you ever purchased one of those build-it-yourself furniture kits? Sure, the picture on the box and the model in the store both looked easy enough to construct, and the instructions said you just needed a screwdriver to build it. However, when faced with the eight dozen screws that spill out of the box, it's clear that you want a faster method.

Luckily, you've got a drill. In short, your drill just served as an enzyme. An enzyme is a substance that allows for a reaction to happen much faster. In this example, the reaction was building the furniture. Note that the enzyme does not become part of the final substance, but merely speeds it up.

Lowering Activation Energy

Sure, using a drill isn't that much faster than doing the first screw or two by hand. But by the time you've done a couple dozen with the screwdriver, your arm is tired and your knuckles are beat up. In short, you don't have the energy to do this anymore. The drill required a lot less energy. In fact, this is the exact term used by scientists.

Many reactions require energy to occur, something called activation energy. Enzymes lower that requirement. Just like using your drill required a lot less energy than doing it all by hand, the enzymes create an environment in which the work can be done at a lower activation energy.

Enzymes at Work

Think about how you use a drill. You match the drill bit to the screw in question and then fire away, right? Again, enzymes act in a very similar way. Each enzyme is matched by a particular bond that it can have with the substance that it is acting upon.

In fact, the name given to this particular kind of bonding is referred to as lock and key, since the enzyme acts as a key that opens the lock of the reaction. If an enzyme cannot unlock a substance, it cannot act on it. It's just like using a Phillips head drill bit with a bunch of flathead screws - the drill bit won't fit into the slot, so it is absolutely useless.

Temperature, Saturation, and pH

If you were building that furniture, chances are you would do some things to control the circumstances under which you were building it. Ideally, you'd do it in a climate-controlled environment without a big crowd around, and preferably not after a particularly large meal. Enzymes work the same way.

Imagine building that shelving system indoors, and then imagine building it in a room where the heat index is above 100! Clearly, you'd work slower in the hotter room. Enzymes are the same way - at temperature extremes, they slow down or altogether stop working. Meanwhile, is that drill going to be much use if all the screws are already fastened?

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