Chapter 5: Enzymes PDF

Chapter 5: Enzymes  Learning Objective To explain how the body is organised and describe, in detail, how digestion occurs. Success Criteria To state what an enzyme is and how they are involved in chemical reactions. To explain how the three enzymes digest s...

Chapter 5: Enzymes  Learning Objective To explain how the body is organised and describe, in detail, how digestion occurs. Success Criteria To state what an enzyme is and how they are involved in chemical reactions. To explain how the three enzymes digest specific foods. To describe how enzymes can be denatured by changing conditions.  Copy and complete the sentences Enzymes Enzymes are , they increase the rates of a chemical reaction without being used up. They are made of and are involved in reactions such as and photosynthesis. They have an where the reaction occurs. The enters the active site and the eventually leaves the active site. Enzymes work like Substrate a and Enzyme changes they are specific shape slightly as Products to a reaction. substrate binds Active site Substrate Enzyme/substrate Products leaving entering complex active site of active site of enzyme enzyme Enzymes Answers Anatomy of enzymes Biological Catalysts Chemical that speeds up chemical reactions are catalysts. So enzyme are biological catalysts (made by living things). Speeds up chemical reaction without being changed or used up. What are Enzymes? 1. All enzymes are proteins. 2. Enzymes are specific. 3. Have prefix of ‘- ase’ at the end of its name. 4. Lowers the amount of activation energy Activati on Energy  Lock & Key Theory One enzyme is specific to one substrate’s chemical reaction. Active Site Place where substrate combines with an enzyme out of its chemical reactions The active site has a unique geometric shape that is complementary to the geometric shape of a substrate molecule, similar to the fit of puzzle pieces. Enzyme, Substrate & Active Site How does an enzyme work? The mode of action of an enzyme (Figure 5.6 of Student’s Book)  Enzyme-Substrate Complex Chemical reaction occurs for the substrate at the active site. One molecule can be broken down into two or more molecules (catabolic) Or two or more molecules can be made into one large molecule (anabolic) Enzymes in Digestion Complete a storyboard to explain how enzymes work. What Is the Title of the Lesson? Crack the Code! A–1 G –7 M – 13 S – 19 Y - 25 B–2 H–8 N – 14 T – 20 Z - 26 C–3 I–9 O – 15 U - 21 D–4 J – 10 P – 16 V - 22 E–5 K – 11 Q - 17 W - 23 F–6 L – 12 R - 18 X - 24 5, 14, 26, 25 13, 5, 19 9, 14, 4, 9, 7, 5, 19, 20, 9, 15, 14 What Is the Title of the Lesson? Crack the Code! Enzymes in digestion  Enzymes in Digestion Why have enzymes in digestion? To break down larger chains into smaller molecules so they can be absorbed into the blood stream. There are 3 types of enzymes in digestion: protease; amylase; lipase.  Carbohydrase  Carbohydrase breaks down carbohydrates into smaller sugar molecules.  It is produced in the salivary glands and the pancreas.  Amylase (an example of a carbohydrase) will breakdown starch in the mouth and in the smallStarchintestine. Sugar molecule molecules Carbohydrase Digestion  Protease Protease breaks down protein into smaller amino acid molecules. Protease will breakdown protein in the stomach and in the small intestine. Amino acid molecules Protein molecule Digestion  Lipase Lipase breaks down lipids into fatty acids and glycerol molecules. Digestion of fat occurs in the small intestine. Fatty acid molecules and Glycerol molecules Fat molecules Lipase Different enzyme, different jobs  Questions Using the information sheet answer the questions in full sentences. amylase 1.What enzyme is produced by the salivary gland? 2.What enzyme breaks down protein? protease 3.What is fat broken down into?fatty acids and glycerol 4.What enzyme works in the stomach? protease 5.What enzymes break down food in the small intestine? amylase, protease and lipase 6.Why is it so important to break down the large molecules? So they can be absorbed by the small intestine into the blood. 7. Where does digestion start? the mouth  Changing Conditions Enzymes are very specific and will only work under certain conditions. If the conditions change too much the enzyme will become denatured. This means the enzymes change shape and the active site no longer works. Conditions that affect the enzyme include temperature and pH. heat pH normal denatured When protein loses their structure due to certain reason, it’s called denaturation. FACTOR AFFECTING ENZYME ACTION 1. pH Levels 2. Temperature  Describe the Graphs As the temperature As the pH increases so increases so does the rate of does the rate of reaction, reaction, until it reaches the until it reaches the optimum, when it then optimum, when the pH becomes too hot and the becomes to high and the rate of reaction decreases. rate of reaction decreases. The enzymes become The enzymes become denatured. denatured.  Optimum Enzyme pH Salivary amylase 6.8 Stomach protease 1.5 - 2.0 (pepsin) Pancreatic protease 7.5 - 8.0 (trypsin) pH Optimum of Enzymes ; Optimum Temperature of Enzymes Helpers! Using Enzymes High-Fructose Corn Syrup  Food Role of lipase Cheese Taste better Vegetable Improve quality of fats Other oil bread Last longer/taste s Dairy better Improve taste LIPASE DOING ITS DAY JOB! food drinks Improves aroma (smell) Sauces Smoother texture Meat/fish Fat removal Health Add essential fatty foods acid  Exam Question Explain how enzymes are used in the digestion of food. (6 marks)  Answers – Any Six Answers Explain how enzymes are used in the digestion of food. (6 marks) Some points that could be covered: Carbohydrase breaks down Carbohydrates into sugars. Amylase breaks down starch into maltose. Produced by the salivary glands, pancreas and small intestine. Lipase breaks down fats into fatty acid and glycerol. Produced by the pancreas and small intestine. Bile neutralises the stomach acid, allowing the enzymes to work better. Bile also emulsifies fat, breaking it down into smaller droplets, enzymes can then break it down easier. Protease breaks down protein into amino acids. Produced by the stomach, pancreas and small intestine. The smaller molecules are absorbed into the blood in the small intestine. The villi provide a large surface area for more absorption of digested food.  Enzyme Match-Up where it is made enzymes food salivary gland, protease group small intestine and lipids pancreas lipase protein pancreas, small amylase intestine starch stomach, pancreas, small intestine Extension What does each enzyme break the larger food molecules into?