5th Year Biology - Enzymes PDF

Enzymes Sources of Energy Solar Cellular Solar Energy: is energy from the sun Cellular Energy: is the energy stored in the bonds of biomolecules Catalysts: a substance that speeds up a reaction without itself being used up in the reaction. Enzymes: Enzymes are catalysts made of protein the...

Enzymes Sources of Energy Solar Cellular Solar Energy: is energy from the sun Cellular Energy: is the energy stored in the bonds of biomolecules Catalysts: a substance that speeds up a reaction without itself being used up in the reaction. Enzymes: Enzymes are catalysts made of protein they speed up a reaction without being used up themselves in the reaction.  Because enzymes are made in living things they are called biological (or organic catalysts). Enzymes Are Proteins – made in ribosomes Are Specific – only work for one substrate. Only works if they have the correct 3-D folded shape. End in ‘ase’ e.g. lipase acts on lipids, amylase works on amylose (starch) Enzyme  Metabolism :is the sum of all chemical reactions that take place within an organism. Catabolic reactions are breakdown reactions Complex (large) molecules  small molecules AB  A + B e.g. Respiration e.g. Digestion - Breakdown of Starch by Amylase Amylase Starch  Maltose Amylase is a catabolic enzyme which works in the mouth Anabolic reactions: are build up reactions Small molecules  Complex molecules A + B  AB e.g. in Photosynthesis An anabolic enzyme, DNA Polymerase joins DNA molecules together.  Factors Affecting Enzyme Activity? Temperatu re pH Anything that changes the shape of an enzyme will reduce the efficiency of the enzyme to speed up a reaction.  Denatu red A denatured enzyme: an enzyme that has lost its ability to function. It has lost its shape and can no longer work.  At very low temperatures ice forms, liquids become solids and enzymes can’t work. As temperature increases molecules start to move and bump into each other causing the rate of reaction to increase. Temperature: as temperature increases the reaction rate increases. The optimum temperature is the temperature the enzyme works best at. Our body’s enzymes prefer 37oC Plant enzymes prefer 25oC pH pH = how acidic or basic (alkali) something is Basic /  All proteins (enzymes) tend to change their shape as the pH changes. Enzymes work over a very narrow pH Most enzymes work at pH 6-8 Outside this they lose shape and get denatured  The optimum or best pH is usually pH 7 An enzyme will only have its correct shape at a specific pH If the pH changes the enzyme becomes less effective The optimum pH is the pH the enzyme works best at mmobilised Enzyme  Immobilisation of Enzymes Enzymes are used to speed up a particular reaction in industry. This saves time and money. The problem with this is the product (sugar) has enzyme mixed in with it in solution so the mixture needs to be separated to  To prevent having to do this the enzyme is trapped in a bead/gel. The substrate can get in and the product can get out but the enzyme cannot get out. Immobilisation of enzymes is the trapping of enzymes in  Bio-processing: is the use of enzyme controlled reactions to produce a product Bio-processing can be used to produce a vast range of products such as cheeses, beer, antibiotics, vaccines, methane gas, food flavours, vitamins and perfumes  If enzymes are used freely dissolved in a vessel it can be very wasteful as they are lost at the end of the process To prevent this problem enzymes are often immobilised or fixed This means they are attached to each other or an inert substance and can be used repeatedly Optimum pH Denatur ed Enzyme Methods of Immobilising Enzymes Attached to each other Attached to insoluble supports Enclosed within a membrane or gel  ADVANTAGES of Can Immobilising Enzymes be reused, saves money as replacing enzymes is expensive Immobilised enzymes remain at the bottom of the reaction vessel at the end of the process, enzyme separation from product is not necessary Very often, increases enzymes  Bio-processing: is the use of enzyme-controlled reactions to produce a product Bio-processing can be used to produce a vast range of products such as cheeses, beer, antibiotics, vaccines, methane gas, food flavours, vitamins and perfumes USES of Immobilising Enzymes: Glucose Isomerase Glucose Fructose (sweeter) Penicillin acylase Penicillin New Antibiotic Lactase  Catalase is an enzyme that is found in a wide range of living things, e.g. liver, radishes, potatoes and celery Converts the toxic substance hydrogen peroxide into water and oxygen  To Investigate the Effect of Temperature on Enzyme Action SAFETY  Equipment/ Graduated Cylinder x2 Apparatus Dropper Used: Blender Beaker Coffee Filter Paper pH buffer 9 solution Hydrogen Peroxide Washing up liquid Celery Ice Water Bath Thermometer Enzyme = _________ (celery) Substrate = _________ _________ Products = Water + Method: 1. Collect all equipment listed 2. Place some pH buffer 9 solution in a graduated cylinder 3. Using a dropper add a drop of washing – up liquid to the graduated cylinder 4. Blend some stalks of celery in water in a blender. Filter this solution into a large beaker using coffee filter paper 5. Add some of the filtered celery solution to the graduated cylinder 7. Stand the graduated cylinders in a large beaker of ice – cold water until they are 0 ͦC 8. Remove the graduated cylinders from the water bath and pour the hydrogen peroxide into the graduated cylinder containing blended celery 9. Note and record the volume at the top of the foam after 2 minutes 10. Calculate the volume of foam produced 11. Repeat steps 2 – 10 at 10 ͦC, 20 ͦC, 30 Result s: Conclusion: The enzyme (catalase) works best at optimum temperature of __________ To Investigate the Effect of pH on Enzyme Action SAFETY  Equipment/ Graduated Cylinder x2 Apparatus Dropper Used: Blender Beaker Coffee Filter Paper pH buffer 4, 7, 10, 13 solution Hydrogen Peroxide Washing up liquid Celery Water Bath Thermometer Method: 1. Collect all equipment listed 2. Place some pH buffer 4 solution in a graduated cylinder 3. Using a dropper add a drop of washing – up liquid to the graduated cylinder 4. Blend some stalks of celery in water in a blender. Filter this solution into a large beaker using coffee filter paper 5. Add some of the filtered celery solution to the graduated cylinder 7. Stand both graduated cylinders in a water bath at 25 ͦC for a few minutes 8. Remove the graduated cylinders from the water bath and pour the hydrogen peroxide into the graduated cylinder containing blended celery 9. Note and record the volume at the top of the foam after 2 minutes 10. Calculate the volume of foam produced 11. Repeat steps 2 – 10 using pH buffers 4, 7, 10 and 13 Result s: Conclusion: The enzyme (catalase) works best at optimum pH of __________  Catalase works best at pH 9, the buffer ensures the pH remains constant at 9 Washing – up liquid traps the oxygen that is released  forming foam Filtration removes blended cells and contents Celery contains the enzyme catalase Hydrogen peroxide is the substrate EXPERIMENT: To Prepare an Enzyme Immobilisation  Equipment/ Beaker Apparatus x3 Used: Stirring rod x3 Electronic balance Graduated Cylinder Syringe Distilled Water Sodium Alginate Yeast Calcium Chloride Method 1. Collect all equipment listed 2. Measure out 10ml of distilled water in a graduated cylinder and pour it into two of the beakers 3. Using an electronic balance, weigh out 0.4g of sodium alginate, pour it into one of the beakers with water and stir to dissolve 4. Weigh out 2g of yeast, add it to the other beaker of water and stir to dissolved 6. Add the dissolved yeast solution to the sodium alginate solution and even mix the two solutions 7. When the two solutions are evenly mixed, draw up the liquid into a 20ml syringe. 8. From a height of 10cm, release the mixture from the syringe into the calcium chloride one drop at a time. Leave to harden for 10 minutes. EXPERIMENT Continued: Examining and application of immobilised enzymes  Equipment/ Apparatus Retort stand x2 Used: Separating funnel x2 Straw x2 Yeast Distilled water Beaker x2 Sucrose Glucose test strips Timer Electronic balance Graduated Cylinder Method 1. Collect all equipment listed 2. Mix 2g of yeast in 10ml of distilled water and pour into one of the separating funnels. 3. Pour the hardened beads into the second separating funnel. 4. Dissolve 1g of sucrose in 100ml of distilled water. 5. Pour 50ml of the sucrose solution into each separating funnel 6. Immediately test the products in the beakers with glucose strips Results Conclusion Enzyme = Sucrase Advantages Disadvantag (Yeast) es Substrate = Beads can be Is generally reused slower Sucrose Product = Glucose Product is separate from substrate Cheaper Can be used for continuous production Summary