ENZYMES BUTTONS Click here Clicking Clicking here will

ENZYMES BUTTONS Click here: Clicking Clicking here will here will bring move reveal will you reveal you back some back to an to the information. aanswer. this page. next page. on the Clicking here will allow you to hear some information topic. Clicking here again will stop the sound. TOPICS Jump to… …enzyme structure. Jump to… …lock and key theory and denaturation (two pages). Jump to… …enzyme reactions (three pages). Jump to… …practice questions (two pages). Jump to… …exam questions (two pages).

ENZYME STRUCTURE Enzymes are proteins made by living cells. They catalyse/increase the rate of chemical reactions, inside and outside cells. Click on the buttons for more information. Forming an enzyme (Higher tier) Enzyme structure amino acids The sequence of amino acids determine the protein shape and therefore its function. active site Sequence of amino acids in a chain active site The shape of the active site is different for each enzyme. This is where the chemical reaction occurs.

LOCK AND KEY THEORY Each enzyme has a specific substrate which fits into the active site as a key fits into a lock. A reaction will then occur and a product will be released. SUMMARY Click on the button for more information. DIGESTING MOLECULES enzyme (lock) substrate Digesting molecules substrate product (key) active site enzyme key substrate lock enzyme – substrate complex enzyme product enzyme recycled BUILDING MOLECULES Building molecules MORE ABOUT THEORY

DENATURATION Enzymes react best at their optimum temperature. This is the point where the rate of reaction is highest. If the temperature is greater than the optimum, the enzyme will become denatured, changing the shape of the active site. The substrate will not be able to bind to the active site and no product will be released. Click on the button for more information. INCREASING THE TEMPERATURE The active site has changed shape. The substrate cannot fit and a reaction will not occur and therefore, no product. enzyme substrate Optimum temperature When the enzyme has denatured it can not be returned to its original shape. active site

RATE OF REACTION – effect of temperature Rate of reaction Enzymes react best at their optimum temperature. This is the point where the rate of reaction is highest. The temperature is high Click on the buttons for more information. Theenzyme’s enzyme and substrate have a The optimum temperature and the The enzyme’s active becoming low kinetic energy. There will is not behave many is 50˚C. enzyme and site substrate a denatured. Although there is more kinetic successful collisions between active site higher kinetic energy. Manythe successful enzyme energy, there will be lesslittle successful and substrate and therefore product collisions will occur between the active siteis collisions the active site and produced inbetween a given time. Notice that the and the substrate resulting in more product. substrate. Eventually eachshape enzyme will enzyme does not change at low substrate become denatured resulting in no product. temperatures. product Temperature (°C) Low temperature Optimum temperature High temperature

RATE OF REACTION– effect of p. H Enzymes react best at their optimum p. H. This is the point where the rate of reaction is highest. Click on the buttons for more information. p. H near optimum Rate of reaction optimum p. H extreme p. H 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 p. H optimum p. H

ENZYME EXPERIMENT In each living cell a poisonous chemical called hydrogen peroxide (H 2 O 2) is produced. Fortunately, each living cell contains an enzyme called catalase which breaks it down it. This equation shows the reaction. Now on click the boxes discover Click theonspeaker icontoon the left thelearn mean volume of this O 2. experiment. to more about hydrogen CATALASE water + oxygen Concentration volume O 2 per minute (cm ) peroxide H 2 O 2 (%) 3 oxygen accumulating Mean O 2 volume per minute (cm 3) measuring cylinder hydrogen peroxide (substrate) potato discs water trial 1 trial 2 trial 3 mean 0 0 0 25 18 22 20 20 50 38 44 38 40 75 59 60 61 60 100 60 62 58 60 H 2 O 2 catalase Hydrogen peroxide concentration (%)

PRACTICE QUESTION 1 Firstly click on any one of the enzyme boxes on the left. Now try to choose the correct substrate and product which corresponds with your chosen enzyme. ENZYME SUBSTRATE PRODUCT

Rate of reaction/ mg product per second PRACTICE QUESTION 2 Rate of reaction optimum p. H Click on the correct sentences. Enzyme A has an optimum p. H of 2. 5. The rate of reaction of enzyme B is higher than A at their optimum p. H. Enzyme B has an optimum p. H of 5 -10. Enzyme A works best in acidic conditions. The enzymes optimum temperature is: 70˚C 50˚C The enzyme has completely denatured at: 0˚C 60˚C 70˚C The rate of reaction is greatest at: 40˚C 50˚C 70˚C

EXAM QUESTION 1 Click on the answers to see how many marks the examiner awarded each response. WJEC Biology 1 Summer 2017 (Foundation) Q 2. 1 mark correct 3 2 4 1 The increase in rate has been described (1 mark). The optimum temperature of 35˚C has not been recognised. The decrease in rate has not been described at temperatures greater than the optimum. An explanation of the decrease is given, not a description. 0 marks It’s the active site that changes shape (1 mark). Therefore, the substrate cannot bind with the active site (1 mark). The rate increases up to 6 a. u. and then the enzyme denatures. The enzyme has changed shape.

EXAM QUESTION 2 Try to answer this exam question. Once you have had a go, click on the looking for. Lock and key. Boiling denatures the enzyme, changing the shape of the active site. The molecule will not fit into the active site. WJEC Biology 2 Summer 2015 (Higher) Q 2. to see the answer the examiner was

EXAM QUESTION 3 Try to answer this exam question. WJEC Biology 2 Winter 2014 (Higher) Q 6. Once you have had a go, click on the looking for. to see the answer the examiner was Enzyme – substrate complex. Active site is {changed/distorted/altered}/bonds in active site are broken; {Substrate/amino acid} cannot {fit/join/lock }; NOT match. Temperature; p. H; NOT PH/Ph Concentration of substrate; Concentration of enzyme; (Reject amount/volume/mass).