To investigate the amount of O2 released at different of concentration of enzyme catalyse in (Yeast).

To investigate the amount of O2 released at different of concentration of enzyme catalyse in (Yeast)

Scientific background:

Introduction:

Many chemical reactions take place inside a cell. The speeds at which the cell reactions take place are controlled by catalyst called enzymes, or we can say enzymes are biological catalyst. Enzyme speed up the rate of reaction without it self being used. Some enzymes, such as pepsin and trypsin, which bring about the digestion of meat, control many different reactions, whereas others such as urease are extremely specific and may accelerate only one reaction. Enzymes are large proteins that speed up chemical reaction. In their round structure, one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, enzyme active site is the method of key and lock this means the active site is lock if the shape of substrate do not match exactly. This ensures that the enzyme is not specific for that chemical reaction.

There are thousand of enzymes in living organisms, and they are specific, this means that each enzyme catalyses a certain chemical reaction.

An enzyme has an active site, which has a unique shape into which only a substrate of same unique shape can be fit. When this substrate fits into the active site it forms products.

Enzymes can be denatured at certain conditions:

Temperature: The rise temperature increases the rate of most chemical reaction; a fall in temperature slows them down. Mostly a rises of 10 oC will double the rate of reaction, but above 50 oC the enzyme being proteins are denature and stop working.

PH: acid or alkaline conditions alter the chemical properties of proteins, including enzymes. The enzymes work bet at a particular level of acidity or alkalinity (PH). So we can say that each enzyme has got its own optimum PH.

Hydrogen Peroxide:

H2O2 is one of the most powerful oxidizers known. H2O2 can be converted into hydroxyl radicals (OH). H2O2 is a natural metabolite of many organisms, which decompose the H2O2 they produce into oxygen and water. H2O2 is also formed by the action of sunlight on water. H2O2 has none of the problems of gaseous release or chemical residues that are associated with other chemical oxidants. And since H2O2 is totally miscible with water, the issue of safety is one of concentration. About the industrial strength of H2O2. It is a strong oxidizer and as such requires special handling precautions. Its primary uses are as a chemical intermediate, as a bleaching agent in the textile and paper and pulp industry and in water treatment operations.

Hydrogen peroxide is formed intracellular as a result of certain enzymatic reactions. Hydrogen peroxide, either from this source or externally applied, generates hydroxyl radicals that initiate lipid per-oxidation chain reactions within exposed cells and can lead to DNA damage and cell death. DNA damage has been demonstrated in bacteria and in cultured mammalian cells. In addition, hydrogen peroxide induced mutation in bacteria, yeast and other fungi.

Prediction:

The rate of reaction is directly proportional to the enzyme concentration. This is due to the fact that when the enzyme concentration is rising it makes more active ...

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Prediction:

The rate of reaction is directly proportional to the enzyme concentration. This is due to the fact that when the enzyme concentration is rising it makes more active sites available to react with the substrate. So more H2O2 decomposed by more yeast.

Aim:

To investigation the of amount oxygen released with different concentration of enzyme called catalyse and the source was yeast.

Preliminary work:

As I wanted to take the idea that how to do this experiment I have arranged some apparatus and set them up. I took 5 ml of yeast and 5 ml of hydrogen peroxide. To measuring the O2 I chose a big syringe. As I put the amount of yeast and hydrogen peroxide in the test tube for reaction, then the gas released collapsed the syringe and I could not obtain the proper reading of O2 released from the preliminary experiment. I have learned how to improve the apparatus then I took Retort stand with a big glass cylinder for my proper course-work readings. Also I have learned to keep time constant for all the reactions.

Apparatus:

5 beaker for different concentration of yeast
Hydrogen peroxide
Yeast of 4%
Retort stand
100 ml Glass cylinder
Distilled water
2 syringe
Side arm Test tube
Water bath
Beehive

The set up diagram shown bellow.

Method:

There are many ways in which the amount of Oxygen released could be affected. I have chosen the concentration of enzyme. 10 ml of 4 % yeast has been taken and accepted it as 100 percent to calculate the different concentration. First the dilute yeast has been made. Five different concentration of yeast that are 100%, 80%, 60%, 40% and 20% are made as I have shown on the table of yeast concentration. To collect out data I measured the amount of O2 produced from the reaction, by letting it pass through a tube and let it displace the water in the measuring cylinder. The experiment carried out three times for each concentration with 3ml of yeast and hydrogen peroxide. The step bellow followed for recording the O2 released during the reaction.

The 3 ml of hydrogen peroxide taken in small syringe.
3 ml of yeast has taken in a small syringe.
Pure the yeast in test tube.
Add 3 ml of hydrogen peroxide.
The test tube closed immediately and the stopwatch started.
The time keeps constant for 1 minute.
The amount of O2 released from the reaction measured by the 100 ml Glass cylinder.
The step a. to g. followed up in experiment 3 times for each five concentration and the amount of O2 released measured.

Table for yeast concentration:

The yeast concentration was 4% but for calculating the concentration I accepted it as 100 %.

Variables:

In this investigation independent variable is enzyme concentration.

Dependent variable is the amount of O2 released which depend on concentration of enzyme.

Fixed variable is time, volume of yeast, concentration of substrate and temperature. The time kept constant for 1 minute in each reaction. Volume of yeast kept constant in 3 ml in each reaction.

Safety: Laboratory coats were worn during the investigation to prevent chemicals from spoiling clothes. Care was also taken whilst handling the chemicals, as hydrogen peroxide is corrosive.

Eye protection is necessary because any contact with eye cause serious damage.
Wearing gloves.

Fair test:

To make the test fair I will do all the experiments in the same room and day hopefully the temperature remains constant. Also the time is kept constant for all the reactions for 1 minute. I used the 100 ml measuring cylinder with rotate stand to make sure that amount of O2 released is kept in cylinder.

Results Table: The rate at which hydrogen peroxide was broken down to water and oxygen in the presence of catalyse.

The Amount of O2 released in experiment with varying concentration of yeast

Conclusion/Analysis:

The graph “ the decomposition of hydrogen peroxide in the presence of Yeast which contain enzyme catalyse” shows the amount of O2 released against concentration of yeast (enzyme). The amount of O2 released increase as the concentration of yeast increase. It also indicates that the enzyme concentration has positive correlation with the rate of reaction for the decomposition of hydrogen peroxide. The reaction was fastest at an enzyme concentration of 100% yeast. At this enzyme concentration there were the greatest number of free active sites available to the substrate molecules so that they could be broken dawn. The rate of reaction increased steadily from 25.7 when yeast is 20% to 44.7 when yeast is 100% concentrated. I have mentioned in my prediction that rate of reaction is directly proportional to the amount of O2 but, my graph show directly proportional because the average data is increasing but the are not in straight line.

Evaluation:

The data that I collected was reasonable for the accuracy of my experiment; it was fairly reliable that the results I collected were mostly expected. Again when I see the graph it is not straight line. I have drawn the graph for the average of 3 experiments that I did for each concentration. There are a few different results that can be determined when I add straight line. I can say there are two anomalous average results, which are far from the straight line drawn. And I think it is not possible to take precise readings from the graph between the plotted points since insufficient readings. To do a more accurate experiment in the future. Several precautions or alteration can be made. For example for experiment of enzyme with hydrogen peroxide. I can use another enzyme like potato discs. And I can use more potato disc to provide more enzymes for decomposing H2O2.The average readings could be improved by repeating to reduce the average of anomalous results. The increase in rate of reaction is the reason of existing more catalyse enzyme that provide the more active site for decomposition of hydrogen peroxide. In this experiment 5 enzyme concentrations were considered. The formula for this chemical reaction is as follows.

2H2O2 H2O+ O2

My result supports the scientific knowledge that I have written about the enzyme and hydrogen peroxide. As concentration increase if provide more active site and the theory of key a lock apply here, because it is the same enzyme to work for decomposition of hydrogen peroxide to water and oxygen gas.