Determine the optimum temperature. Define enzyme. An enzyme is a biological catalyst. Define optimum temperature. Optimum temperature is the temperature at which the enzyme has it maximum activity highest rate of reaction Q. From your graph of activity against temperature, determine the optimum temperature. Predict the the optimum temperature of a digestive enzyme such as pancreatic amylase.
Since pancreatic amylase is a digestive enzyme its optimum temperature would be boy temperature ie.
Catalase Enzyme Coursework - A-Level Science - Marked by tinterscolesca.ml
Temperature is a measure of the kinetic energy of the molecules in a system. As the temperature increases, the kinetic energy and thus the number of random collisions of enzyme with substrate increases per unit time. With the increase in frequency in the number of collisions, the probability of the enzyme and substrate colliding in the correct orientation ie. Hence rate of reaction increases with temperature increases, up until the optimum temperature is attained. Account for the decline in the slope after the optimal temperature is attained.
A further increase in the temperature beyond the optimal temperature leads to disruption of the weak bonds of the enzyme - enzymes are proteins. The unfolding of the protein due to the disruption of bonds is called denaturing. During denturation the precise configuration of the active site is lost. As the active sites are lost, the catalytic activity and hence rate of reaction decrease. Calculate the temperature coefficient Q10 for your enzyme controlled reaction. The temperature coefficient Q10 for an enzyme controlled reaction between 0 and 45oC is 2.
To obtain catalase from a substance such as potato would involve crushing it and with that method you would never be sure of the concentration of the catalase. If the catalase was used up then another potato would have to be crushed and this could produce catalase of a totally different concentration which would lead to inaccuracies in the experiment making this an unfair test. To ensure this is a fair test all the variables except for the concentration of Hydrogen Peroxide must be kept the same for all the experiments.
Variables that must not be altered include Temperature, yeast concentration, type of yeast, batch of yeast, volume of yeast, volume of hydrogen peroxide, air pressure and humidity. When measuring the volumes of Hydrogen Peroxide, Yeast and Water the measurement should be taken by looking at the scale at an angle of 90 degrees to it to avoid any parallax error.
I predict that as the substrate concentration increases, the rate of reaction will go up at a directly proportional rate until the solution becomes saturated with the substrate hydrogen peroxide. When this saturation point is reached, then adding extra substrate will make no difference. The rate steadily increases when more substrate is added because more of the active sites of the enzyme are being used which results in more reactions so the required amount of oxygen is made more quickly. Once the amount of substrate molecules added exceeds the number of active sites available then the rate of reaction will no longer go up.
This is because the maximum number of reactions are being done at once so any extra substrate molecules have to wait until some of the active sites become available. All the times are in seconds. The average results are all written down to one decimal place because although the stopwatch gives results to two decimal places it is impossible to get accurate times to two decimal places due to the fact that our reaction times are not fast enough to stop the stopwatch precisely.
I then worked out the rates of the reactions with the equation.
From these rates I was able to plot a graph of the rate of reaction against concentration of Hydrogen Peroxide. If you double the concentration of Hydrogen Peroxide then the rate of reaction doubles as well. I would expect the rate to increase two times if the Hydrogen Peroxide concentration is increased two times because there are twice as many substrate molecules which can join onto the enzymes active sites. There may also be some experimental error which causes the inaccuracies. This is shown by the gradient of the graph going down.
At this point virtually all the active sites are occupied so the active sites are said to be saturated with Hydrogen Peroxide. Increasing the Hydrogen Peroxide Concentration after the point of saturation has been reached will not cause the rate of reaction to go up any more. All the active sites are being used so any extra Hydrogen Peroxide molecules will have to wait until an active site becomes available.
The theoretical maximum rate of reaction is when all the sites are being used but in reality this theoretical maximum is never reached due to the fact that not all the active sites are being used all the time. The substrate molecules need time to join onto the enzyme and to leave it so the maximum rate achieved is always slightly below the theoretical maximum.
The time taken to fit into and leave the active site is the limiting factor in the rate of reaction.
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Limitations To help make this experiment more accurate, I repeated it three times and then used the average of all the results to plot a graph with a line of best fit. I tried to keep all the variables except for the concentration of Hydrogen Peroxide the same for all the experiments. However, in reality it is impossible to keep all the variables precisely the same. For example:. This will slightly affect all the results but as I carried out all the three steps in the same way for all the experiments it should not make any difference to the overall result.
As the scale on the pipettes shows the volume to the nearest mm3 the volume of the solutions that I used should be correct to the nearest mm3. The volume of gas in the test tube to start with is slightly affected by the amount which the bung is pushed down each time, if the bung is pushed down further then the volume in the tube will be less so the 30cm3 of gas is reached faster.
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The plotted results on the graph produce a straight line of best fit to begin with which then goes into a curve of steadily decreasing gradient. This is probably due to an experimental error involving one of the factors mentioned above. This experiment could be improved in a number of ways.
It could be repeated more times to help get rid of any anomalies. A better overall result would be obtained by repeating the experiment more times because any errors in one experiment should be compensated for by the other experiments. The problem of the delay between pouring in the Hydrogen Peroxide, bunging the test tube and starting the stopwatch could have been limited by getting another person to start the stopwatch when the hydrogen peroxide was poured into the tube. This is a real A-level school project and as such is intended for educational or research purposes only.
Extracts of this project must not be included in any projects that you submit for marking. Doing this could lead to being disqualified from all the subjects that you are taking. You have been warned.
If you want more help with doing your biology practicals then have a look at 'Advanced Level Practical Work for Biology' by Sally Morgan. If you want more detailed biology information then I'd recommend the book 'Advanced Biology' by M. Tags: A-level , biology , enzyme , experiment , project , substrate concentration. This entry was posted on Thursday, June 5th, at pm and is filed under Life. You can follow any responses to this entry through the RSS 2.
Relationship Between Catalase and Hydrogen Peroxide
You can leave a response , or trackback from your own site. Would be great to use this is a guideline. Obviously not to copy.
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H, yes you can use this title. Good luck with your coursework.