The Effect of Temperature On the Enzyme Activity of Rennin

An enzyme up close

The pH affects the rate of a reaction because they themselves have a pH too. They have a pH and temperature optimum at which they can work at. The pH or heat can affect the enzyme by changing the shape of its active site. Sometimes denaturing can occur and that is when the shape of the active site changes permanently.

A FAIR TEST

To make this a fair test you have to take into account that some factors will make the results inaccurate.

One of the main problems of this method is that there is no way of keeping a certain temperature constant. This is an extremely important factor because the whole experiment is dependant on the temperature being accurate or there is no experiment. The way this factor was controlled was by letting the water get to the desired heat and then when it changed the heating appliance would be taken away if it went above its desired temperature or added if it went below its desired temperature.

Another factor that might affect the experiment is the amount that is poured in the test tubes. Every time you pour something out of a test tube some of the product poured is lost because part of the product does not go to its desired destination. Some of may drop on the table or drip down the side of the test tube. This is important again because the amount of solution there is can affect the experiment and make the results incorrect. This factor was controlled by having the amount of solution used in the experiment increased by about 1mml, hence making up for the lost fluid.

THE RANGE OF RESULTS

I plan to take results for the time taken for milk to curdle from 20 degrees to 80 degrees inclusive. Research shows that enzymes are not active above 80 degrees or below 20 degrees. So anything in between those will be acceptable for this experiment to help draw better and easier conclusions.

I plan to take two results for each or repeat results so that I can draw better conclusions. This will be especially handy for when there are any anomalous results, which occur. Some of the results will need to be repeated for the lower temperatures because when they heat up past their desired temperature it is harder for it to cool down because room temperature, for example is above 20 degrees. It is harder to keep constant temperature at a lower heat.

THE APPARATUS & HOW THEY WILL BE SET UP

The apparatus that will be used are as follows:

8 bungs a Bunsen burner

A ceramic mat a gauze

8 measuring cylinder a pipette

A stopwatch 8 test tubes

A thermometer a test tube rack

A tripod a water bath

The tripod will be placed on a ceramic mat so it does not burn the table. On top of that there will be the gauze and the water bath in which, where the thermometer and test tubes will be placed. The Bunsen burner will be positioned under the water bath for maximum performance. The other test tubes will be in the test tube rack.

The pipette will be on hand to move the solution from one test tube to the other and the stopwatch will be next to the Experiment to be able to see when to stop it. The measuring cylinders will be next to the test tube rack to be able to measure the amount of solution. The bungs will be on top of the test tubes.

SAFETY PRECAUTIONS

Safety is very important and that is why it comes before the method. First of all, chairs were put under the desks so there was no danger of tripping over. Ties were tucked in so they would not get near the flame and most of all; goggles were worn to prevent any foreign bodies coming into contact with the eye. i.e. boiling water. To uphold the safety the correct attitude of character was kept.

HYPOTHESIS

I predict that as the temperature goes up so will the enzyme activities. This will happen up to a certain point where the enzyme activity will start to denature. The graph below can show this theory more easily.

At (a) you can see as you move up in temperature, there will be a larger proportion of activation energy which, means the molecules will collide more often.

At (b) the activation energy is more than at (a) and they are still colliding but the temperature has affected the active sites hence leading to denaturing.

METHOD

I plan to set up the apparatus as below. First the correct amounts of milk and rennin have to be put in a test tube using a pipette. Then both of the test tubes with the rennin and milk will be heated with a Bunsen burner to the desired temperature. To keep an eye on the temperature a thermometer will be used.

When the test tubes are at the correct temperature the rennin will be poured into the milk and then stirred for a few seconds. Then a bung will be placed firmly on top of the test tube to stop any thing getting into the mixture. As soon as the two solutions come to mix the stopwatch will be started because that is when the rennin starts to work on the milk.

After a minute the test tube is checked to see if the milk has curdled. As soon as it does the stopwatch is stopped and the time is recorded. The diagram below shows how the experiment was set up.

OBTAINING

HOW THE EQUIPMENT WAS USED & HOW THE RESULTS WERE TAKEN?

The apparatus were set up as on page 8. First of all the milk and rennin will be sized up by using a measuring cylinder and a pipette. The Bunsen burner will be used to heat the water bath because you can easily adjust the amount of heat it gives out by opening or closing the hole on it. A bung will be used to place on top of the test tube to stop any foreign bodies from entering the mixture. Ceramic mats will be used to prevent the Bunsen burner from burning the working area. A stopwatch will be used to record the times taken.

The results will be taken using a stopwatch. The stopwatch will be started once the two substances come into contact with each other and stopped when the milk curdles or does not change after a sufficient time, e.g. 45 minutes.

From background research it has shown that enzymes do not work above certain temperatures like 80 degrees. That is why in my results the word denatured might be in a gap where there should be a time because is what the enzyme is doing.

STEP - BY - STEP DIAGRAMS

The diagrams below will show how I carried out this experiment Step - by - step.

.

The correct amounts of

Rennin and milk will

Be poured into their

Test tubes.

2.

Both of the test tubes

were heated to the desired heat using a Bunsen burner and a thermometer.

3.

When the temperature

was correct, the two

were mixed and then

stirred for a few seconds.

4.

The stopwatch will be started once the solutions are mixing together.

TEMPERATURE

TIME TAKEN FOR MILK TO CURDLE

A B

/TIME

A B

20

61

73

0.0062111

0.0057803

30

83

89

0.0120481

0.0112359

40

00

18

0.01

0.0084745

60

246

202

0.0040650

0.0049504

70

__

__

__

__

5.

When the milk has curdled the stopwatch will be stopped and the time recorded.

THE RESULTS

ANALYSING

ANALYSIS

Below are the results, I collected and presenting them in this way may help me reach better conclusions or find patterns.

The graph on page 14 shows that at 30 degrees the enzyme works best and works worst 60. At 70 degrees the enzymes has denatured. It also shows that the second time I carried out the experiment the milk took longer to curdle.

The graph on page 15 shows the enzyme activity. It shows that the enzyme works best at 30 degrees and worse at 70 and 80 degrees. The lines on the graph both show the same pattern.

The second graph is clearly the upside down version of the first graph. This could be due to the fact the second graph is made from doing 1/ from the first graph.

A GRAPH TO SHOW THE TIME IT TAKES MILK TO CURDLE

A GRAPH TO SHOW THE ENZYME ACTIVITY

CONCLUSION

I have found out that the enzyme rennin works best between 30 and 40 degrees. It works worst above 40 degrees and not at all above 70 degrees. The reason it does not work above 70 degrees is probably because it has denatured. Also, it shows that it does not work best below 30 degrees either. The temperature between 30 and 40 degrees is room temperature or body temperature. Even though these results show that the enzyme works best between 30 and 40 degrees, it may not, its just that, it's the temperature that they have to work at so over time it has got used to the temperature.

The reason the reactions happens faster at 40 than at 20 degrees is because with higher temperature comes more activation energy. When there is more activation energy the enzymes and reactants come into contact more often because they are moving faster. The reason the rennin worked best at 30 degrees was probably because it was at its optimum. The reason the enzyme activity starts to go down is probably because the high temperature has changed the shape of the active site and when that is changed no reactions will take place due to the fact only certain substrates fit into certain active sites. After 70 degrees the enzymes must have denatured meaning the shape of the active sites must have changed permanently.

My hypothesis is correct because it matches my results. The reaction rate did go up to a certain point where after it started to denature. It even shows this in my results because at first the reaction goes up till it gets to its peak at 30 degrees and then starts to go down rapidly representing denaturing.

EVALUATING

EVALUATION

This experiment is about the effects of temperature on the enzyme rennin. That is why I chose this method to carry out the experiment with because it gets the results, it safe and it is quite accurate.

The results are accurate because the method chosen was a good one and there were no anomalous results. There were no problems carrying out the experiment either.

The experiment could be improved slightly if there was electric water bath so it could keep the temperature the same and make the results that much more accurate. Also if there were a way that the amount of enzyme and milk poured in could be accurate too would help to make the experiment true.

BIBLIOGRAPHY

Letts GCSE class workbook

Class Exercise book

WORD COUNT

Number of words; 2,252

Number of lines; 464

Number of paragraphs; 149

Henry Aboagye-Brobbey 5B

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