Metabolism & Enzymes

1. Metabolism & Enzymes Thursday 1st March

2. Starter – how many words can you make from: • LOCK AND KEY

3. Task 1: Notes • The chemical reactions that take place in your cells are called Metabolism • The rate of metabolism is controlled by enzymes • Metabolism reactions can be divided into 2 groups those that break down matter and those that build complex molecules.

4. Enzymes – the key to it all Almost all chemical reactions that take place inside living things are controlled by enzymes. Enzymes are biological catalysts. They speed up chemical reactions without being used up. Every cell in every plant and animal contains many different types of enzyme. Each enzyme catalyzes a different reaction.

5. Task 2: Questions • What is an enzyme? • What are enzymes made from? • Where are enzymes found and what do they do?

6. activesite Enzymes – the ‘lock and key’ model Enzymes are very specific about what reaction they catalyse. Only molecules with exactly the right shape will bind to the enzyme and react. These are called reactant molecules, or the substrate.

7. activesite Enzymes- Active site The part of the enzyme with which the reactant binds is called the active site.This is a very specific shape. The reactant is said to fit like a ‘key’ in the ‘lock’ of the enzyme’s active site. This way of describing how an enzyme works is called the ‘lock and key’ model.

8. Task 3: Draw this lock and key diagram

9. Enzymes are denatured beyond 40OC 400C Enzymes and temperature Enzyme-catalyzed reactions take place across a range of temperatures, usually 20-45°C. All enzymes work best at only one particular temperature, called the optimum temperature. Different enzymes have different optimum temperatures.

10. Denatured

11. Enzymes breaking down starch • Starch is a large complex carbohydrate • To be used in the body it needs to be broken down into smaller sugar molecule (glucose) • The enzyme Amylase helps break down starch into sugars

12. Experiment – Enzyme activity • 2 tubes – label ‘enzyme’ and ‘no enzyme’ • Add 20mls of coloured starch solution into each tube you have labeled • Add a few drops of iodine to the solution until blue/black in colour • Add amylase to the tube you have labelled enzyme and stir • Place both beakers in a warm water bath • Predict what you think will happen • Leave for 10 mins • Test both tube for glucose using Benedicts test

13. Results and discussion • Record change in appearance of beakers • Record whether glucose was present in each beaker Analyse • Compare results you have obtained to your prediction • If glucose was present explain where it came from • Explain why the beakers were warmed to around 30oC