Enzyme Function

1. Enzyme Function D. Crowley, 2007

2. Enzyme Function • To know what can affect how well an enzyme works

3. Absorption • Digested food molecules are absorbed through the small intestine (into our blood) • Once in the blood, the digested food molecules are carried around the body, to where they are needed • Only small, soluble molecules can pass through the wall of the small intestine

4. Villi • The inside wall of the small intestine needs to be thin, with a really big surface area • This allows absorption to happen quickly and efficiently (so we absorb as much food as possible) • To get a big surface area, the inside wall of the small intestine is lined with tiny villi (one of them is called a villus) • These stick out and give a big surface area. They also contain blood capillaries to carry away the absorbed food molecules.

5. Enzyme Function • Enzymes only break down one type of food – e.g. lipase only breaks down fat (lipids); amylase only breaks down carboydrates; protease only breaks down protein • The rate at which enzymes break food down can be affected by two main factors: - • pH • Temperature • What do you think the optimum temperature if for enzymes in the body? • What about pH?

6. Experiment • Trypsin is an enzyme which breaks down protein • If Trypsin is added to milk it will break down the milk, turning it from cloudy to translucent • You need to carry out an experiment to find out how the temperature of the Tryspin affects how quickly the milk is broken down • You will have 3 boiling tubes of milk • To each you will add some Tryspin which is at different temperatures • You need to time how long the solution went from being cloudy to translucent

7. Procedure • Take 3 boiling tubes, and fill them each with 10ml of milk – place them in a rack • Add 10ml of cold Trypsin to one boiling tube with milk in, and begin the timer – time how long it takes for the solution to become transparent • Repeat this with the second boiling tube, but this time add 10ml warm Trypsin • Repeat this with the third boiling tube, but this time add 10ml boiling Trypsin • Record all your results

8. Explanation • Explain why when the Trypsin was cold the solution turned clear slowly • Explain why when the Trypsin was warm the solution turned clear quickly • Explain why boiling the Trypsin caused the solution to remain cloudy

9. Temperature • This experiment shows that enzymes work best at a given different • If it is too cold the enzyme takes a long time to break the food molecules down • But if it is too hot the enzyme may not function at all – it has been denatured • Enzymes in the human body usually denature above 45oC