Enzymes exist in our bodies and they speed up reactions that take place inside us. They are called biological catalysts as they are important in biological reactions such as digestion.
If we didn't have enzymes in our digestive system, our breakfast cereal would still get broken down and absorbed, but much slower. In the presence of some important enzymes it is a much speedier process.
The three main enzymes involved in digestion are:
Carbohydrase - breaks down carbohydrates like cereal, bread and pasta
Protease - breaks down proteins like meat and eggs
Lipase - breaks down fats like butter and oils
Now each of these three enzymes is slightly different to the others, so they only work on their own reactions. Lipase for example, will not speed up the breakdown of proteins.
Let's have a go at some questions about enzymes!