1 What are biological catalysts?Baseline (Flightpath D): To be able to define the terms ‘catalyst’ and ‘enzyme’. Further (Flightpath C&B ): To be able to describe the properties of enzymes. To use the lock and key theory and collision theory to explain enzyme action. Challenge Flightpath A): To be able to explain why enzymes are specific and are denatured by high temperature and extremes of pH.
2 What are biological catalysts?Learning Objective To be able to describe the properties of enzymes. To use the lock and key theory and collision theory to explain enzyme action.
3 Elephants toothpaste https://www.youtube.com/watch?v=ezsur0L0L1c
4 Definitions Catalyst – Speeds up a chemical reaction which is not used up in the reaction Enzyme – Biological catalyst that speeds up reactions. Each enzyme interacts with a specific substrate molecule
5 How enzymes work – lock and key methodActive Site Enzyme has the same shaped active site as the substrate Reaction is catalysed New products formed
6 Boardworks GCSE Additional Science: Biology EnzymesThe lock and key model Teacher notes This four-stage animation demonstrates the principles of the ‘lock and key’ model. While showing the animation, the specific shape of the active site could be highlighted. Suitable prompts could include: What is special about the shape of the active site? Is the enzyme the ‘lock’ or the ‘key’?
7 Enzymes are protein molecules, and so are made up of amino acidsEnzymes are protein molecules, and so are made up of amino acids. Most enzymes contain between 100 and 1,000 amino acids. These amino acids are joined together in a long chain, which is folded to produce a unique 3D structure.
8 Match the enzyme to the substrate1 2 3 4 5 A B C D E
9 ANSWERS 1 2 3 4 5 C E D A B
10 Why will enzyme 1 not work on substrate D?Why will protease not work on starch?
11 Catalyst effect on Hydrogen PeroxideHydrogen peroxide naturally decomposes to release oxygen. The presence of a catalyst will increase the rate of decomposition. This experiment looks at how different catalysts affect the decomposition rate. Method Measure out 100ml of hydrogen peroxide into the measuring cylinder and pour into the conical flask. The bung and delivery tube should be connected to the gas syringe. Add 0.5g of the manganese (IV) oxide to the conical flask, insert the bung and start the stopclock. Time how long it takes for 20ml of gas to be produced. Repeat using 0.5g potato Risks Wear goggles when measuring out liquids. Wipe up any spills straight away. Ensure you work in the centre of the bench and that all glass ware is kept away from the edge. Use a dustpan and brush to clean up any breakages if they occur.
12 Planning Independent Variable: Dependent Variable: Control Variable:
13 Time to produce 20 ml of gasCatalyst Time to produce 20 ml of gas manganese (IV) oxide potato
14 Exam prep (a) Complete the table to give one site where digestive substances are made (4) (b) Describe two ways that the mouth can break down starchy foods. (2) (c) Describe how the liver helps to digest fats. (Total 8 marks) Digestive substance One site of production bile amylase lipase protease