Effect of Temperature on Enzyme Catalase Activity in a Potato

Effect of Temperature ( C ? ) on Enzyme Catalase Activity in potato Aim: To investigate the Effect of temperature (10, 37, 60) Celsius (C ? ) on enzyme catalase activity in potato using 2% of hydrogen peroxide (H202) as the substrate measuring the height (cm) of oxygen gas (bubbles) and calculating the volume of oxygen bubbles produced (cm3) Introduction: Enzymes are biological catalysts that speed up metabolic reactions without being affected. They lower the activation energy needed to start a reaction. Enzymes are affected by several factors including PH, Substrate concentration; Temperature & other factors.

Each enzyme has an optimum temperature at which its activity is the highest, below this optimum temp, the kinetic energy of molecules decrease , therefore the collisions between the active site of the enzyme and substrate decreases , as a result the enzyme activity will decrease , so decreasing the rate of the reaction If the temp. Exceeds the optimum temp. The kinetic energy between molecules increase therefore collisions increase leading to the change in the tertiary structure of the enzyme and in this case active site is lost and the enzymes will be denatured so the reaction will slow down &stops.

Catalase is an enzyme, found basically in all living cells. It breaks down hydrogen peroxide (waste product) into water and oxygen. 2H? O? 2H2O+O2 As predicted, the enzyme catalase activity would be the highest at 37c ? (Optimum temp. )if increased to 60c ? then the enzyme would be denatured and if decreased to 10c ? (very low temp. ) then the reaction would be slow. Variables: Dependent: Height of oxygen bubbles (cm) using a ruler. Independent: Temperature (10c ? , 37c ? , 60c ? ) using three different water baths each adjusted to a specific temp . Controlled: 1.

Number of potato cubes: 3 cubes of potatoes were used in each trial at each different temp. If changed, whether decrease or increase, then the number of enzymes (active site) available would change, therefore affecting the rate of the reaction. 2. Size of potato cubes with dimensions 1cmx1cmx1. 5cm . This is controlled by cutting all potato cubes with same dimensions using a ruler & a cutter. If changed, then this would affect the rate of enzyme activity, therefore affecting the results. 3. Volume of hydrogen peroxide: 15cm3 of hydrogen peroxide was measured using graduated cylinder for each trial at different temp.

If changed then the rate of enzyme activity would change, therefore results won’t be accurate. 4. Concentration of hydrogen peroxide: 2% of hydrogen peroxide was used through all trials this is prepared by adding 20cm3 of H2o2 to 1000cm3 of water. If changed it would affect the rate of enzyme activity since substrate concentration is one of the factors that affect enzyme activity. 5. Volume of liquid detergent: 2drops of liquid detergent were added to each test tube throughout the experiment. If changed, then this will affect the height of oxygen bubbles measured cm3 therefore the results won’t be accurate. . Time: time was recorded for 2 minutes; if changed this will affect the results. Materials: * 27 cubes of potato each with dimensions 1cmx1cmx1. 5cm. * 15cm3 of 2% hydrogen peroxide for each trial. * 9 test tubes * Water adjusted to (60c ? ,37c ? &10c ? adding ice) * 2drops of liquid detergent in each test tube * Cutter * Ruler * 100cm3 graduated cylinder * Stopwatch * 1000cm3 volumetric flask * 50cm3 beaker Procedure: 1. Use the cutter, and ruler to cut 27 cubes of potato with dimensions 1cmx1cmx1. 5cm 2. Adjust the water bath temp one at 60c ? , the other one at 37c ? amp; last one at 10c ? adding ice. 3. Place 3 potato cubes in each of the three test tubes placed at 10c ?. 4. Leave the test tubes at 10c ? for 10min. 5. Add 2 drops of detergent for each test tube. 6. Measure 15cm3 of 2% hydrogen peroxide for each test tube using graduated cylinder. 7. Add 15cm3 of 2% H2o2 to each test tube, and immediately start the stop watch recording time for 2 min. 8. After 2 min exactly, use the ruler to measure the height of oxygen bubbles (cm). 9. Repeat steps 3 to 8 at a different temp (60c ? ,70c ? ). 10. Record all data in an organized table. Processing and Presenting Data: Table (1): Shows the height of oxygen bubbles produced (cm) at different temp. (C ? ) TemperatureC ? ± 0. 05| Height of oxygen bubbles produced after 2 minutes (cm)| | Trial 1| Trial 2| Trial 3| 10. 00| 2. 00| 6. 00| 2. 00| 37. 00| 3. 00| 4. 50| 1. 50| 60. 00| 3. 00| 2. 00| 2. 00| Table (2): Shows mean height in (cm) for oxygen bubbles ± 0. 05 and volume of oxygen bubbles (cm3)±0. 05 at different temp (C ? ) Temperature C ? ± 0. 05| Mean height (cm) for oxygen bubbles ± 0. 05| Volume of mean height of oxygen bubbles cm3 0. 05| 10. 0| 3. 33| 16. 34| 37. 00| 4. 86| 23. 84| 60. 00| 2. 06| 10. 11| * Sample calculations 10c ? 1. Mean height of oxygen bubbles in cm. T1+T2+T33= 2+6+23= 3. 33cm 2. Volume of oxygen bubbles cm3 Volume of cylinder: ? r2xh 3. 14x (1. 25)2x3. 33=16. 34cm3 Discussion: As shown in table (2) as temperature increased from 10c ? to 37c ? , the mean height in cm of oxygen bubbles increased from 3. 33cm to 4. 86cm. Aa temperature increase from 37c ? to 60c ? the mean height cm of oxygen bubbles decreased from 4. 86cm to 2. 06cm. Reffering to the table (2) and graph , as temp. ncreased from 10c ? to 37c ? the volume of oxygen bubbles (cm3) increased from 16. 34cm3 to 23. 84cm3. As temp increased from 37c ? to 60c ? the volume of oxygen bubbles produced (cm3) decreased from 23. 84cm3 to 10. 11cm3. Each enzyme has an optimum temp. at which the rate of enzyme activity is the highest. Above the optimum temp the kinetic energy of molecules increases therefore the collisions between the active site and the substrate increase and as a result the enzyme would lose its 3D structure and active site and the enzyme would be denatured.

This is shown in the graph, as the volume of oxygen bubbles cm3 decreased from 23. 84cm3 to 10. 11cm3 at 60c ?. Below the optimum temp the kinetic energy of molecules decreases ,therefore the collisions decrease and the enzyme would slow down and the rate of energy decreases as it’s shown in table (2) the volume of oxygen bubble decrease from 37c ? to 10c ?. According to our results in table (2) and graph, the optimum temp was 37c ? at which rate of enzyme catalase activity was the highest as the highest volume of oxygen bubbles was produced 23. 84cm3.

The results obtained matched the hypothesis which stated that 37c ? is the optimum temp for enzyme catalase to break hydrogen peroxide which is a toxic product into water & oxygen. Evaluation & Improvements: 1. Size of potato cubes . Potato cubes were cut into cubes of dimensions 1cmx1cmx1. 5cm using a ruler and a blade which was a source of error since all cubes vary slightly in size which means the concentration of catalase enzyme is different. A potato cutter that cut the potato into equal sizes . 2. Height of oxygen bubbles measured by a ruler. This was inaccurate method.

Volume could be measured instead in height using gas Syringe which will give more accurate results 3. Volume of detergent. 2 drops of detergent were measured using a dropper. A pipette can be used which will give more accurate results. Done BY: JIHAN AL-BUKHARI 9A -------------------------------------------- [ 1 ]. [ (Jones, 2009) ] [ 2 ]. "Introduction to Enzymes. " Factors Affecting Enzyme Activity (). N. p. , n. d. Web. 16 Nov. 2012. . [ 3 ]. "Effect of Temperature on Enzyme Activity. " Effect of Temperature on Enzyme Activity. N. p. , n. d. Web. 16 Nov. 2012. .