2. Enzymes in Digestion L.O: To understand how the enzymes in the digestive system help digestion Starter: digestion know the answer

3. Chew a piece of bread in your mouth, do not swallow yet! What do you notice about the taste? Can you explain what is happening? -Your teeth are physically breaking down the large chunks -Your saliva is mixing with the food making it slippery and easier to swallow -Enzymes in your saliva begin to break down the carbohydrates into sugars

4. Digestive system Now label your digestive system describing the jobs of the organs

5. Bile and The Liver Bile is a chemical produced in the liver and stored in the gall bladder. It has 2 functions: 1)It neutralises stomach acid and produces alkaline conditions for enzymes to work in 2)It emulsifies (“breaks down” fats: Fat globules Fat droplets

6. How Enzymes Work Enzymes have some important properties: They are proteins They are influenced by temperature and by pH They work best at certain temperatures and pH, eg 37 C They can be destroyed by extremes of heat and pH Each enzyme works on only one particular reaction Each enzyme molecule can affect a single reaction over and over again Most enzymes have names with ‘ ase ’ at the end, eg, Carbohydrase acts on carbohydrates Protease acts on proteins Lipase acts on fats (lipids) Record the chemical equations on the next few slides to show the action of the 3 enzyme groups.

7. The digestion of carbohydrates can be represented by the following equation. SugarsCarbohydrates carbohydrase Enzyme driven reaction carbohydrase

8. Enzymes for digesting proteins sites of enzyme attack Protein is made up of chains of amino acids. There are over 20 different kinds of amino acid. The enzymes that digest proteins must be able to break the chemical bonds between the different amino acids. Enzymes that digest protein are known as proteases. amino acids The digestion of proteins can be represented by the following equation. protease ProteinAmino Acids

9. Fat in our food The enzymes that digest fats must be able to break the chemical bonds between the glycerol phosphates and the fatty acids. Fats are made up of a molecule of glycerol phosphate attached to three fatty acid molecules. Fats are also known as lipids. site of enzyme attack fatty acids glycerol phosphate Fat digestion can be represented by the following equation: lipase Fat Fatty Acids + Glycerol Phosphate

10. EnzymesCarbohydrate (eg starch) Enzymes bind to carbohydrate Enzymes break the links between the sugars Enzymes breaking down large carbohydrate molecules into smaller sugar molecules that can pass across the gut wall Blood Cell Intestine Wall Blood Vessel Wall How Enzymes Work

11. Where are the enzymes made and used? Digestive enzymes are different to other enzymes because they work outside of your cells. They are produced in glands, the pancreas, and in the gut lining. Different enzymes work at different pH levels so are found and used in different parts of the digestive system (as we have already found out the intestine is alkaline to help break down fats).

12. Mouth Carbohydrase (Amylase) Starch  Simple sugars e.g. glucose Stomach Protease (Pepsin) Protein  Amino Acids Duodenum Lipases / proteases (Trypsin) / Carbohydrases Fats  Fatty Acids and Glycerol Protein  Amino Acids Starch  Simple sugars e.g. glucose The enzymes are made in the glands, pancreas and the gut lining Slightly Alkaline Acidic Alkaline Add this information onto your diagram by colouring the areas and doing a key

13. Enzymes in digestion Enzymes can be produced by the body to help _______. When they come into contact and react with food they break it down into ______ pieces which can then pass into the ______: Carbohydrase (produced in the mouth, pancreas and small intestine) breaks _______ (a carbohydrate) down into glucose: Protease (produced in the stomach, pancreas and small intestine) breaks _______ down into amino acids: Lipase (produced in the pancreas and small intestine) breaks fats (_____) down into fatty acids and glycerol: Words – blood, lipids, proteins, digestion, starch, smaller Bloodstream

14. Digesting a Burger Now describe what happens to a burger during digestion including what parts are digested where because of the enzymes needed.

15. Multiple-choice quiz