Starter: Match the graph with the factors that affect enzymes. Reaction Rate. Reaction Rate. Jun 21 12:04 p.m.

Transcription

1 Starter: Match the graph with the factors that affect enzymes Reaction Rate Reaction Rate Reaction Rate Reaction Rate Temperature ph Enzyme Concentration Substrate Concentration Jun 21 12:04 p.m. Quick Quiz! 1. What is an enzyme? 2. What are the 4 main things that affect enzyme function? 3. Explain the difference between the lock and key and the Induced Fit model of enzyme function Jun 23 8:44 a.m. 1

2 What do these have in common? Quick Photosynthesis Review a) Describe the purpose of photosynthesis b) Explain how the structure AND location of chloroplasts affect the process of photosynthesis Jun 21 12:07 p.m. 2

3 Nature and Properties of Enzymes Biological found within living organisms Catalyst substance which can speed up a chemical reaction Proteins in nature Specific in action one kind of enzyme will catalyse only one kind of chemical reaction Protein Mechanism of enzyme action Active site : the place where substrate binds with the enzyme Each active site can only allow specific substrate to fit in Substrate the chemicals in the reaction 3

4 Enzymes work by lowering the activation energy required for a reaction to get started. Enzymes Enzymes are biological catalysts. They are proteins which are found in living things, and it is their job to speed up reactions. Enzymes speed up reactions by reducing the amount of energy required for the reaction to get underway (activation energy). Each enzyme is specific to one type of reaction. An enzymes active site will only allow a specific substrate to bind. 4

5 Theories... The Lock and Key Model describes the fitting in of specific substrate molecules into the active site of the enzyme. The Induced fit model describes the way that an enzyme changes shape when the substrate molecules lock and how this causes a reaction that leads to a product being formed. Action of enzyme Apr 8 7:14 p.m. 5

6 Enzyme Function... Factors affecting enzyme activities : Temperature ph Factors affecting rate of enzymatic reactions : Temperature ph Enzyme concentration/available surface area Substrate concentration/available surface area Co enzymes (Cofactors) enzyme inhibitors How temperature effects enzyme activity Low temperature : Lower reaction rate (and enzyme activity) Enzymes become inactive Higher temperature : Higher reaction rate (and enzyme activity) But too higher temperature leads to denaturing 6

7 Effect of temperature on enzyme activity denature Denaturation is a permanent process When an enzyme is denatured, its catalytic function is lost permanently, it can never become active again. Do not say it's DEAD!! 7

8 Effect of ph on enzyme activity Too extreme ph can destroy the enzymes Optimum ph : the ph value at which the enzyme has the highest activity Pepsin in the stomach Enzyme Activities can be affected by: ph Temperature (collision theory) Low temp can inactivate enzymes and high temp can denature them. Extreme ph can also denature enzymes. The rate of enzyme reactions can be affected by: Temperature ph Enzyme concentration / Available surface area Substrate concentration / Available surface area Apr 8 7:03 p.m. 8

9 Co-Enzymes (or Co Factors) Some enzymes are made of protein alone. Others consists of 2 parts: protein and another chemical called a co factor. Co enzymes are simply "helper" molecules that ensure the substrate attaches and that the chemical reaction occurs. Apr 8 7:03 p.m. Handout on enzymes Jun 22 10:07 a.m. 9

10 Enzymes are found in both animals and plants, and have important roles in their metabolism. (a) Describe the general purpose of enzymes. (b) Explain the difference between the lock and key and induced fit models of enzyme activity. You may use diagrams in your answer if you wish. Jun 21 12:06 p.m. Home Learning: Some of the factors that affect the rate of enzyme activity within cells include the amount of substrate, the enzyme concentration, coenzymes, and enzyme poisons (inhibitors). Discuss how any THREE of these factors can change the rate of activity within cells Jun 21 12:07 p.m. 10

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