1. Enzyme Function D. Crowley, 2007

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

3. Absorption Digested food molecules are absorbed through the small intestine (into our blood) 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 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 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 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) 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) 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. 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 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: - 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 do you think the optimum temperature if for enzymes in the body? What about pH? What about pH?

6. Experiment Trypsin is an enzyme which breaks down protein 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 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 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 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 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 second boiling tube, but this time add 10ml warm Trypsin Repeat this with the third boiling tube, but this time add 10ml boiling Trypsin Repeat this with the third boiling tube, but this time add 10ml boiling Trypsin Record all your results Record all your results

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

9. Temperature This experiment shows that enzymes work best at a given different 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 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 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 45 o C Enzymes in the human body usually denature above 45 o C