ENZYMES

Introduction to enzymes video

Perform chemical reactions in your body Are PROTEINS 3-D shape is very important Name is based on the substrate it works on— always ends in “-ase” –Lactase works on: Lactose –sucrase works on: Sucrose –Protease works on proteins

ACTIVATION ENERGY Energy “hump” which molecules have to get over in order to react DRAW IT Exothermic reaction: releases energy –Exo exits Products have less energy than reactants Example: burning

Endothermic reaction: absorbs energy endo – enters Products have more energy than reactants Example: photosynthesis DRAW IT

Check your Understanding 1.Enzymes are what kind of food nutrient? 2.What is the difference between and endothermic and an exothermic reaction? Give an example of each 3.What does an endothermic reaction look like on a graph? An exothermic reaction?

CATALYSTS Make reactions go faster –Lower the activation energy required for the reaction –Reactions can take place at a lower temperature than normal Enzymes are the catalysts in your body Not part of final product; can be re-used

How enzymes work Enzyme binds to active site on substrate “Lock-and-key” model: active site and enzyme have to fit exactly “Induced fit” model: the enzyme changes shape slightly as it binds to the substrate

Enzyme video clip

Cofactors Some enzymes require a cofactor or a coenzyme in order to work In your body, the cofactors are vitamins and minerals

How enzymes are denatured Denature – enzymes can unfold slightly –won’t fit substrate anymore Caused by high/low pH or temp

Check Your Understanding 1.Explain how enzymes work as catalysts in your body 2.Explain the difference between the lock- and-key model and the induced-fit model of enzyme activity 3.What are the cofactors in your body? 4.What does denature mean? What would cause an enzyme to become denatured?