What Is The Effect Of Ph On Enzyme Activity
IB Biology
Sheran Gu
Meghan Lena
Nov. 15th
Influence of pH on Enzyme Activities
How does the pH of solution influence the speed of enzyme activities?
Enzymes are protein catalysts and chemical that speed up chemical reaction without being involved in the reaction. They are involved in the human digestive system to help people digest food more efficient. Food are substrates to be break down and absorb through the digestive system in the body. Substrate is a molecule that bond with the active site of enzyme to transfer in to one or more products. It attaches to enzyme, form enzyme-substrate complex and leave enzyme unaffected (Eed). Most enzymes and substrate have their specific geometric shape, so Most enzymes act with only one substrate that …show more content…
fit in the shape to produce products. In this lab, hydrogen peroxide is matched with catalyses that will break hydrogen peroxide down to water and oxygen. The rate of enzyme catalysis can be affected by the surroundings. It is dependent on substrate concentration, temperature and pH levels. Temperature that is too high or too low might denature enzymes. Substrate concentration that is too high might slow down the reaction rate. In this Lab, the relationship between pH solution and Enzyme activity is studied. The influence of pH solution on Solutions with different pH level can alter the activity of enzyme catalyses. Enzyme are only active in limited range of pH, which means that they work better in certain pH levels than other, because of denaturation. Enzymes that work above or below the rage may be working inefficiently or remaining inactive (Eed).
If pH level of solution is higher or lower than seven, it will slow down or stop the rate of enzyme activity. This is because enzymes may be denatured in a too high or too low pH solution and may cease to have any reaction at all. Enzyme activity functions best in its optimum pH.
Independent variables pH of the solution
Dependent variables
The rate of enzyme activities
The time of reaction
Control group
Substrate concentration
Temperature
Amount of catalase
Hydrogen Peroxide
Catalyse
NaOH
HCl
Beaker
Test Tube
Graduated Cylinder (10 mL)
Pasco sensor
Plastic Pipet
(Figure #1)
Prepare 5 beakers, 5 test tubes, 7 Cylinders and 7 pipets.
Use pipets to put 6 and 20 drops of NaOH in the beakers half filled with water to make pH 9 and 11.5 solutions. (Pasco sensor is used to check)
Use pipets to put 6 and 20 drops of HCl in the beakers half filled with water to make pH 4 and pH2 solutions. (Pasco sensor is used to check)
Fill a beaker with pure water to make pH 7 solution.
Use Cylinder to measure and put 4 mL of Hydrogen Peroxide in each test tubes (5 in total).
Use Cylinder to measure and put 4 mL of each pH solution (pH 2, 4, 7, 9, 11.5) in each test tubes. Label each tube.
Use cylinder to measure and put 4 mL of Catalyse in the tube with pH 2 solution. Start the timer and observe the reaction and stop the timer when reaction is over. Record.
Repeat step 7 to record the time of reaction in pH 4, 7, 9 and 11.5 solution.
Repeat the experiment (step 1 to 8) two more times to get accurate data.
In the experiment, the reaction start immediately after putting 4 mL of catalyses in to the test tube that contains 4 mL of pH solution and 4 mL of substrate (Hydrogen Peroxide). While the reaction start, there are a lot of bubbles formed (see in figure #2). The amount of bubbles decrease while the time pass. While the bubbles stop to form, the reaction is over. Through observation, it is easy to see the different amount of bubbles produced in different test tubes when catalyses are put into solutions. In pH 7 solution, bubbles are produced a lot that even goes out of the test tube, but disappear very fast too. In pH 4, 9 and 11.5 solution, bubbles also are produced a lot at the beginning, but disappear slower. No bubbles are produced in pH 2 solution in all three trials.
Figure #2 shows the processing of the experiment. Count from left to right, the pH solutions are pH 2, pH 4, pH 7, pH 9 and pH 11.5
Table #1 shows the data of three trials collected through the experiment.
Table #2 shows the average time of reaction and the rate of enzyme activity. Average time of reaction is calculated from the datas of three trials. The rate of enzyme activity is calculated by dividing the average time from 1 to show the reaction rate of catalyses in each solution.
Graph #1 shows the graph of data of all three trials and the average time.
Graph #2 shows the graph of the reaction rate of average rate of catalyses in each solution. Figure #2
(Table #1)
(Table #2)
(Graph #1) (Graph #2)
PH solution that is lower or higher than neutral water (pH 7) slows down or stops enzyme activity with substrates in the solution.
The datas collected in this lab showed that both acid and basic solution slow down the enzyme activity and enzyme catalyse works better in neutral solution. The data overall shows that catalyses react slowest in acid solution and react fastest in the neutral solution. There is no reaction in ph 2 solution happened and the reaction in ph 4 solution is obviously slower than that in neutral solution and basic solution. In Graph #2, the highest point of reaction rate is at pH 7 and the lowest point of reaction rate is at pH 2. It shows that when pH is far from the optimum ph for enzyme activity, it will stop the activity. In pH 4 solution, the average time of reaction is 158 sec which is more than double of the average time of reaction in pH 7 solution. When pH is still lower but not that far from optimum pH, enzyme activity will obviously slow down. The time of reaction in basic solution is relatively faster than that in acid solution. The average time of reaction in pH 7 is only 82 sec and in pH 11.5 is 118 sec. Although it is still slower than the time of reaction in neutral solution, it indicates that catalyzes react better and faster in basic solution than acid solution. It also shows that pH solution that is higher than optimum pH for enzyme activity will slow down the enzyme activity. Graph #1 clearly indicates the curve of time change that support the hypothesis, If pH level of solution is higher or lower than seven, it will slow down or stop the rate of enzyme
activity.
Compare to the published Data, the result of this experiment is slightly different. This experiment suggests that The reaction rate of catalyses in basic solution is relatively faster than that in acid solution. The curve of reaction rate shows in published data is different from the curve of reaction rate in this experiment in Graph #2. The curve of reaction rate in published data is symmetric (Park
, which means, the reaction rate in acid and basic solution should be similar, while datas from this experiment suggests that the reaction rate in basic solution is higher than acid solution.
This lab overall successfully answer the research question and get accurate data to support the conclusion. The lab is designed to test the reaction of catalase in different pH solutions. It worked really well that the lab clearly showed the difference of the reaction rate through observation. This lab helped to answer the research question, because it shows the reaction time of each solution and catalase and reflects the rate of reaction. However, there are also some parts that did not work well in the experiment. It is hard to observe the changes in bubbles during the lab, especially when the reaction is close to the end. In three trials, the time of reaction in same pH solution in different trial has a large difference. For example. The time of reaction in pH 4 solution in first trail is 121 sec, while in the second trial is 176 trial. This indicates the inaccuracy of observing the bubbles. It is hard to determine whether the reaction end or not. Another error is that the size of test tube is not big enough to hold all the bubbles produced when catalyses are put into the solution. Bubbles overflow a little bit. This might influence the data of the lab, because some solution goes out of the test tube and may not react with catalyse. But not solution in all five tubes come out. Only pH 7 and pH 9 solution overflow, because they react faster at the beginning. Due to these errors, the data collected may not be 100% accurate, but it is overall answer to the research question. To improve the lab and make data more accurate, it may be better to change the way of measure the reaction rate. It is not accurate to measure the time of reaction, because the amount of bubbles produce is not accurate. It will be more accurate, if it is possible to measure the amount oxygen it produces, because hydrogen peroxide are broken by catalyses to oxygen and water . The amount of oxygen it produced can indicate the reaction rate in the solution.
Eed, John. "Factors Affecting Enzyme Activity." DigitalCommons@C.O.D.College of Dupage, 1 Apr. 2012. Web. 13 Oct. 2014. <
>.
Park, Chul-Won, and Erik Zipp. "Effects of Temperature and PH on Enzyme Kinetics." Effects of Temperature and PH on Enzyme Kinetics. Rpi.edu, 2000. Web. 11 Oct. 2014. <
>.
Sheran Gu
Meghan Lena
Nov. 15th
Influence of pH on Enzyme Activities
How does the pH of solution influence the speed of enzyme activities?
Enzymes are protein catalysts and chemical that speed up chemical reaction without being involved in the reaction. They are involved in the human digestive system to help people digest food more efficient. Food are substrates to be break down and absorb through the digestive system in the body. Substrate is a molecule that bond with the active site of enzyme to transfer in to one or more products. It attaches to enzyme, form enzyme-substrate complex and leave enzyme unaffected (Eed). Most enzymes and substrate have their specific geometric shape, so Most enzymes act with only one substrate that …show more content…
fit in the shape to produce products. In this lab, hydrogen peroxide is matched with catalyses that will break hydrogen peroxide down to water and oxygen. The rate of enzyme catalysis can be affected by the surroundings. It is dependent on substrate concentration, temperature and pH levels. Temperature that is too high or too low might denature enzymes. Substrate concentration that is too high might slow down the reaction rate. In this Lab, the relationship between pH solution and Enzyme activity is studied. The influence of pH solution on Solutions with different pH level can alter the activity of enzyme catalyses. Enzyme are only active in limited range of pH, which means that they work better in certain pH levels than other, because of denaturation. Enzymes that work above or below the rage may be working inefficiently or remaining inactive (Eed).
If pH level of solution is higher or lower than seven, it will slow down or stop the rate of enzyme activity. This is because enzymes may be denatured in a too high or too low pH solution and may cease to have any reaction at all. Enzyme activity functions best in its optimum pH.
Independent variables pH of the solution
Dependent variables
The rate of enzyme activities
The time of reaction
Control group
Substrate concentration
Temperature
Amount of catalase
Hydrogen Peroxide
Catalyse
NaOH
HCl
Beaker
Test Tube
Graduated Cylinder (10 mL)
Pasco sensor
Plastic Pipet
(Figure #1)
Prepare 5 beakers, 5 test tubes, 7 Cylinders and 7 pipets.
Use pipets to put 6 and 20 drops of NaOH in the beakers half filled with water to make pH 9 and 11.5 solutions. (Pasco sensor is used to check)
Use pipets to put 6 and 20 drops of HCl in the beakers half filled with water to make pH 4 and pH2 solutions. (Pasco sensor is used to check)
Fill a beaker with pure water to make pH 7 solution.
Use Cylinder to measure and put 4 mL of Hydrogen Peroxide in each test tubes (5 in total).
Use Cylinder to measure and put 4 mL of each pH solution (pH 2, 4, 7, 9, 11.5) in each test tubes. Label each tube.
Use cylinder to measure and put 4 mL of Catalyse in the tube with pH 2 solution. Start the timer and observe the reaction and stop the timer when reaction is over. Record.
Repeat step 7 to record the time of reaction in pH 4, 7, 9 and 11.5 solution.
Repeat the experiment (step 1 to 8) two more times to get accurate data.
In the experiment, the reaction start immediately after putting 4 mL of catalyses in to the test tube that contains 4 mL of pH solution and 4 mL of substrate (Hydrogen Peroxide). While the reaction start, there are a lot of bubbles formed (see in figure #2). The amount of bubbles decrease while the time pass. While the bubbles stop to form, the reaction is over. Through observation, it is easy to see the different amount of bubbles produced in different test tubes when catalyses are put into solutions. In pH 7 solution, bubbles are produced a lot that even goes out of the test tube, but disappear very fast too. In pH 4, 9 and 11.5 solution, bubbles also are produced a lot at the beginning, but disappear slower. No bubbles are produced in pH 2 solution in all three trials.
Figure #2 shows the processing of the experiment. Count from left to right, the pH solutions are pH 2, pH 4, pH 7, pH 9 and pH 11.5
Table #1 shows the data of three trials collected through the experiment.
Table #2 shows the average time of reaction and the rate of enzyme activity. Average time of reaction is calculated from the datas of three trials. The rate of enzyme activity is calculated by dividing the average time from 1 to show the reaction rate of catalyses in each solution.
Graph #1 shows the graph of data of all three trials and the average time.
Graph #2 shows the graph of the reaction rate of average rate of catalyses in each solution. Figure #2
(Table #1)
(Table #2)
(Graph #1) (Graph #2)
PH solution that is lower or higher than neutral water (pH 7) slows down or stops enzyme activity with substrates in the solution.
The datas collected in this lab showed that both acid and basic solution slow down the enzyme activity and enzyme catalyse works better in neutral solution. The data overall shows that catalyses react slowest in acid solution and react fastest in the neutral solution. There is no reaction in ph 2 solution happened and the reaction in ph 4 solution is obviously slower than that in neutral solution and basic solution. In Graph #2, the highest point of reaction rate is at pH 7 and the lowest point of reaction rate is at pH 2. It shows that when pH is far from the optimum ph for enzyme activity, it will stop the activity. In pH 4 solution, the average time of reaction is 158 sec which is more than double of the average time of reaction in pH 7 solution. When pH is still lower but not that far from optimum pH, enzyme activity will obviously slow down. The time of reaction in basic solution is relatively faster than that in acid solution. The average time of reaction in pH 7 is only 82 sec and in pH 11.5 is 118 sec. Although it is still slower than the time of reaction in neutral solution, it indicates that catalyzes react better and faster in basic solution than acid solution. It also shows that pH solution that is higher than optimum pH for enzyme activity will slow down the enzyme activity. Graph #1 clearly indicates the curve of time change that support the hypothesis, If pH level of solution is higher or lower than seven, it will slow down or stop the rate of enzyme
activity.
Compare to the published Data, the result of this experiment is slightly different. This experiment suggests that The reaction rate of catalyses in basic solution is relatively faster than that in acid solution. The curve of reaction rate shows in published data is different from the curve of reaction rate in this experiment in Graph #2. The curve of reaction rate in published data is symmetric (Park
, which means, the reaction rate in acid and basic solution should be similar, while datas from this experiment suggests that the reaction rate in basic solution is higher than acid solution.
This lab overall successfully answer the research question and get accurate data to support the conclusion. The lab is designed to test the reaction of catalase in different pH solutions. It worked really well that the lab clearly showed the difference of the reaction rate through observation. This lab helped to answer the research question, because it shows the reaction time of each solution and catalase and reflects the rate of reaction. However, there are also some parts that did not work well in the experiment. It is hard to observe the changes in bubbles during the lab, especially when the reaction is close to the end. In three trials, the time of reaction in same pH solution in different trial has a large difference. For example. The time of reaction in pH 4 solution in first trail is 121 sec, while in the second trial is 176 trial. This indicates the inaccuracy of observing the bubbles. It is hard to determine whether the reaction end or not. Another error is that the size of test tube is not big enough to hold all the bubbles produced when catalyses are put into the solution. Bubbles overflow a little bit. This might influence the data of the lab, because some solution goes out of the test tube and may not react with catalyse. But not solution in all five tubes come out. Only pH 7 and pH 9 solution overflow, because they react faster at the beginning. Due to these errors, the data collected may not be 100% accurate, but it is overall answer to the research question. To improve the lab and make data more accurate, it may be better to change the way of measure the reaction rate. It is not accurate to measure the time of reaction, because the amount of bubbles produce is not accurate. It will be more accurate, if it is possible to measure the amount oxygen it produces, because hydrogen peroxide are broken by catalyses to oxygen and water . The amount of oxygen it produced can indicate the reaction rate in the solution.
Eed, John. "Factors Affecting Enzyme Activity." DigitalCommons@C.O.D.College of Dupage, 1 Apr. 2012. Web. 13 Oct. 2014. <
>.
Park, Chul-Won, and Erik Zipp. "Effects of Temperature and PH on Enzyme Kinetics." Effects of Temperature and PH on Enzyme Kinetics. Rpi.edu, 2000. Web. 11 Oct. 2014. <
>.