Structure and action of enzymes Introduction to enzymes video to watch

Enzyme video What is an enzyme? Enzymes are proteins, produced by organisms, that speed up the rate of chemical reactions. They are known as biological catalysts.

What are the properties of enzymes? They are all proteins Each enzyme catalyses one reaction They can be used again and again They are affected by temperature They are affected by pH

Key words

Reactions that enzymes catalyse are divided into 3 types: Breaking large molecules into small ones e.g. in nutrition large food molecules broken down to smaller molecules Building up larger molecules from small ones e.g. glucose molecules are joined together to make glycogen and stored in liver. Converting one small molecule into another

How enzymes work Enzymes work on substances called substrates The reaction takes place on a part of the surface of the enzyme called the active site Enzymes are very specific (fit to certain reaction only). To catalyse a reaction, enzyme molecule and substrate molecule need to meet and join together by a temporary bond. Each molecule has a special shape and an active site into which its substrate molecule fits exactly.

Summary questions p.37 Question 1, 2 and 3

Prep Draw the ‘Lock and Key’ model on page 37 Describe using ‘Lock and Key’ how enzymes work.