This is an biology lab report example about enzyme concentration and the activity of catalase. This biology lab report example can be used in order to figure out how to write a lab report for biology courses. The headings of the biology lab report example are given below.
Aim
To investigate the effect of enzyme concentration on the activity of catalase.
Research question
How does the concentration of catalase where Saccharomyces cerevisiae is the source of enzyme affects the rate of the process of the break down of hydrogen peroxide will be measured by Vernier oxygen gas sensor where the values of temperature, pH, medium, substrate concentration are kept constant?
Hypothesis
As the enzyme concentration is increased, the activity of catalase will increase until a point and then it will stay the same.
Introduction
Chemical reactions can be speeded up by a few ways, one of which is the use of catalysts. A catalyst is a substance that speeds up a reaction by decreasing the activation energy without being affected by the reaction or being used up. Enzymes are biological catalysts that speed up reactions.
A Substrate is a substance on which Enzymes act. Enzymes are spesific for particular substrates. Enzymes work best when some conditions such as pH, temperature and ion concentration are at optimum values. Every enzyme has a spesific optimum value that it works. If the optimum values are not provided, the reaction will proceed in a low rate or there will be no reaction at all.
Hydrogen Peroxide (H_{2}O_{2}) is a reactive chemical that is formed as a by-product in cellular reactions. It must be removed to prevent it from disturbing chemical reactions in the cell. Catalase is an enzyme that breaks down Hydrogen Peroxide to water and oxygen, which are harmless, and thus Hydrogen Peroxide is a substrate for catalase enzyme. Hydrogen Peroxide is broken down by catalase as in the following equation;
2(H_{2}O_{2}) à2H_{2}O + O_{2}
The enzyme, Catalase can be obtained from assaccharomyces cerevisiae and in this experiment Catalase will be obtained from assaccharomyces cerevisiae.
Oxygen is a product of the break down of Hydrogen Peroxide and in this experiment, the rate of reaction will be calculated by measuring the Oxygen given off with a Vernier Oxygen Probe.
Method
- 0.5, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25, 2.50 grams of yeast are measured with a digital balance.
- Each of the different amounts of yeast are poured into different beakers and the beakers are named from 1 to 9 with respect to the amount of yeast it contains.
- Take a syringe and fill the syringe with a 10% Hydrogen Peroxide solution.
- Yeast is put into the special flask of the Vernier gas sensor, which has a neck that fits with the gas sensor so that there is no gas escaping from the flash when the reaction occurs.
- Add the Hydrogen Peroxide solution into the flask that contains yeast. After adding the Hydrogen Peroxide solution, place the vernier gas sensor so that no oxygen gas escapes.
- Repeat the experiment with all the different amounts yeast and take three trials for each amount of yeast.
- Record your data in a table.
- Calculate the rate of Oxygen production for each trial and plot the graph of your data.
Data Collection and Processing
Aspect1: Recording the raw data
By making use of the amount of O_{2} gas produced with every amount of yeast used, it is possible to educe the affect of enzyme concentration on the activity of catalase. Increasing amount of oxygen gas given off means increasing activity of catalase. Three trials are taken for each sample of yeast.
Amount of yeast used (g)(±0.01 g) | Amount of oxygen gas given off (ml)(± 0.10 ml) | ||
Trial 1 | Trial 2 | Trial 3 | |
0.50 | 12.50 | 12.55 | 12.55 |
0.75 | 14.20 | 14.10 | 14.20 |
1.00 | 15.50 | 15.55 | 15.55 |
1.25 | 17.00 | 17.20 | 16.80 |
1.50 | 17.50 | 17.40 | 18.60 |
1.75 | 18.70 | 18.90 | 19.10 |
2.00 | 19.20 | 19.70 | 20.20 |
2.25 | 20.20 | 20.60 | 19.40 |
2.50 | 21.40 | 20.60 | 21.40 |
Table 1: Shows the relationship between the amount of yeast used and the amount of oxygen gas given off.
Aspect 2: Processing the raw data
As a step to make a conclusion about the affect of enzyme concentration on the activity of catalase an interrelation should be found between the enzyme concentration and the amount of oxygen gas given off. The way that will be used in this experiment to find the interrelation is plotting a graph. For each sample of yeast, three trials are taken to make the experiment more accurate. To plot the graph of amount of yeast used versus the amount of oxygen gas given off, the arithmetic mean values for each sample should be calculated. Arithmetic mean is the central tendency of a collection of numbers taken as the sum of the numbers divided by the size of the collection.^{1}
Assuming a set of n values from 1 to n, shown mathematically as A={a_1,a_2,a_3,…,a_n} , the general formula for arithmetic mean is;
Formula 1: The general formula of arithmetic mean.
((Value of 1^st element) + (Value of 2^nd element) + … + (Value of n^th element))/n
For the experiment, there are three trials and thus 3 values. To find the Arithmetic mean of these 3 values the following formula can be generated and used.
Formula 2: The general formula for the arithmetic mean of the trials for each yeast sample used in this experiment.
((Value of 1^st trial) + (Value of 2^nd trial) + (Value of 3^rd trial))/3
Finding the arithmetic mean of the first sample of yeast;
The general formula is generated, as in Formula 2, so the arithmetic mean of the three trials in the first sample can be found by inserting the values into the formula.
(12.50 + 12.55 +12.55)/3=12.53
The arithmetic mean of the oxygen gas given off for each sample can be calculated by following the same way.
Amount of yeast (g)(±0.01 g) | Mean volume of Oxygen gas given off (ml)(± 0.10ml) |
0.50 | 12.53 |
0.75 | 14.17 |
1.00 | 15.53 |
1.25 | 17.00 |
1.50 | 17.83 |
1.75 | 18.90 |
2.00 | 19.70 |
2.25 | 20.07 |
2.50 | 21.13 |
Table 2: Shows the mean volume of Oxygen gas given off for each sample amount of yeast used.
Calculating average percentage uncertanity
To find the average percentage uncertanity, first of all, it is needed to find the percentage uncertainties for the mean volume of Oxygen gas given off for each sample. The general formula for percentage uncertanity is;
Formula 3: General formula of percentage uncertanity
Percentage uncertanity=Uncertanity/(value (mean))×100
Formula 3 can be specialized for this experiment as below;
Percentage uncertanity=0.10/(Average volume of O_2 given off)×100
Formula 4
Percentage uncertanity=0.10/12.53×100=0.80
Finding the percentage uncertanity of the average volume of O_{2 }given off with the first sample amount of yeast.
The percentage of the average volume of O_{2 }given off with the first sample can be found by using Formula 4.
Following the same path, the percentage uncertainties for the other samples can be found. When Formula 4 is applied to all the samples, the values in the following table can be found as the uncertanities of the samples.
Amount of yeast (g)(±0.01 g) | Percentage Uncertainty (%) |
0.50 | 0.80 |
0.75 | 0.71 |
1.00 | 0.64 |
1.25 | 0.59 |
1.50 | 0.56 |
1.75 | 0.53 |
2.00 | 0.51 |
2.25 | 0.50 |
2.50 | 0.47 |
The percentage uncertanities for all samples are found, thus the average percentage uncertanity can be found by using Formula 1. There nine values and according the Arithmetic mean and thus Formula 1, the sum of the all values of percentage uncertanities should be divided by 9.
As found in the above equation, the average percentage uncertanity for this experiment is 0.59%.
Aspect 3: Presenting Processed Data
To find the interrelation between the amount of yeast used and the volume oxygen produced, it is a good way to draw a graph. The graph can be plotted by using technology. By using a computer software called Graphical Analysis, the graph can be plotted. For the graph, the data in Table 2, which contains the mass of yeast used and volume of oxygen produced, should be used. As found in the earlier steps, the average percentage uncertanity is 0.59%. By using percentage uncertanity, error bars can be added to the graph.
Graph 1: Graph of the relation between the amount of yeast and the volume of oxygen gas produced.
Conclusion And Evaluation
Aspect 1: Concluding
By checking over Graph 1, it can be seen that the slope of the graph decreases as the mass of the yeast used increases. Thus, the results and the graph supports my hypothesis.
Aspect 2: Evaluating Procedure
The percentage uncertanity of the experiment is 0.59% and the results support my hypothesis but there can be some errors that affect the accuracy of the experiment. After doing the experiment, I relized some points that can make my results inaccurate.
In total, I made 27 trials but in the laboratory, there were two different packets of yeasts of different brands and I used yeasts from both of the packets. There can be differences between the yeasts in the two different packs. The second mistake I did is that, when starting the reaction I couldn’t immediately place the vernier gas sensor on the flask so there can be some gas escaped from the flask while trying to place the gas sensor. In the research question, I stated that temperature is kept constant but as I was doing the experiment at the same time with my friends in the same laboratory so the temperature values could be different while taking different trials so my results can be inaccurate in this way.
Aspect 3: Improving The Investigation
To improve the investigation, some steps can be taken. First of all, the observer should be careful about using the same species of yeast. Secondly, the observer should use a different design to reduce the oxygen gas loss while placing the vernier oxygen gas sensor or pouring the yeast or H_{2}O_{2} into the flask. If those steps are taken, the experiment will give more accurate results.
References
- <http://en.wikipedia.org/wiki/Arithmetic_mean>, 30.10.2012
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