Biology for Kids
What are enzymes?
Enzymes are special types of proteins. Like all proteins, enzymes are made from strings of amino acids. The function of the enzyme is determined by the sequence of amino acids, types of amino acids, and the shape of the string.
What do enzymes do?
Enzymes are responsible for a lot of the work that is going on in cells. They act as catalysts in order to help produce and speed up chemical reactions. When a cell needs to get something done, it almost always uses an enzyme to speed things along.
Enzymes are Specific
Enzymes are very specific. This means that each type of enzyme only reacts with the specific type of substance that it was made for. This is important so enzymes don't go around doing the wrong thing and causing chemical reactions where they are aren't supposed to.
How Enzymes Work
Enzymes have a special pocket on their surface called an "active site." The molecule that they are supposed to react with fits neatly right into that pocket. The molecule or substance that the enzyme reacts with is called the "substrate."
The reaction takes place between the enzyme and the substrate at the active site. After the reaction is complete, the new molecule or substance is released by the enzyme. This new substance is called the "product."
Things that Affect Enzyme Activity
The environment of the enzyme and the substrate can affect the speed of the reaction. In some cases the environment can cause the enzyme to stop working or even unravel. When an enzyme stops working we call it "denatured." Here are some things that can affect enzyme activity:
- Temperature - The temperature can affect the reaction rate. The higher the temperature, the faster the reaction will occur. However, at some point the temperature will become so high that the enzyme will denature and stop working.
- pH - In many cases the pH level, or acidity, of the environment around the enzyme and substrate can affect the reaction rate. An extreme pH (high or low) will typically slow the reaction or even stop the reaction altogether.
- Concentration - A higher concentration of substrate or enzyme can increase the reaction rate.
- Inhibitors - Inhibitors are molecules that are specially made to stop the activity of enzymes. They may just slow down the reaction or stop it altogether. Some inhibitors bond with the enzyme causing it to change shape and not work correctly. The opposite of an inhibitor is an activator which can help to speed up the reaction.
- Enzymes don't get used up after they do their job. They can be used over and over.
- Many drugs and poisons act as inhibitors to enzymes. Some snake venoms are inhibitors.
- Enzymes are often used in industrial applications such as food processing, paper manufacturing, and detergents.
- There is an enzyme in your saliva called amylase that helps to break down starches as you chew.
- Enzymes play an important role in breaking down our food so our bodies can use it. There are special enzymes to break down different types of foods. They are found in our saliva, stomach, pancreas, and small intestine.
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