The effect that temperature has on enzyme activity.

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INVESTIGATING THE EFFECT OF TEMPERATURE ON THE RATE OF ENZYME ACTIVITY.

To investigate the effect that temperature has on enzyme activity I am going to use the enzyme amylase, which is used as a biological catalyst to break down starch, which cannot pass through the gut wall due to the size of the molecules, into smaller ones. Amylase is a carbohydrase, which converts starch to simple sugars in the Salivary Glands. Three features of all enzymes are:

They are always proteins.

They are specific in their actions and each enzyme controls one particular type of action.

The enzymes are not changed in the reaction which they take part in, therefore they can be used over and over again.

Enzymes work by constantly moving around and colliding with substrates. There is one particular substrate for each enzyme. When it collides with the correct one, the substrate fits the depression, which is otherwise known, as the "active site." The reaction then takes place and the products of reaction leave the active site. The whole process is repeated.

I predict that the enzymes will work at there fastest at around 37C. Both extracellular enzymes and intracellular enzymes are designed to work at body temperature, as they are biological catalysts and they are designed to speed up chemical reactions that take place in our body, inside and outside cells. This is the right temperature for the random movement of molecules, so that they collide as often as possible, without being destroyed. Without enzymes the reactions would be slow and we would not be able to live.

At 0C the enzymes will work slowly to break down the starch. At a lower temperature the enzymes will have little energy and this would make the constant movement extremely slow and therefore the substrate molecule, in this case starch, and the molecule of the right enzyme, amylase, will not collide as often therefore slowing down the process.

At 80C the enzymes will not work. The enzymes will not work at a high temperature as they are destroyed by heat. All enzymes are made out of proteins, this means that they are destroyed or deformed by heat. The starch would not fit into the active site of the amylase as the depressions on the surface have been destroyed/changed by the extreme temperatures. The substrate cannot "lock" in to the active site. Most enzymes are designed to work at a temperature of around 37C, although most of them can work up to 45C, before they are destroyed.

Apparatus.

APPARATUSUSE

Water BathsTo maintain the temperature that the enzymes are working at.

Specimen TubesTo place the solution of starch and amylase in.

Syringe (5ml and 2ml)To add the starch and amylase to the specimen tube

Spotting tilesTO see the progression of the effect of the amylase has had on the starch

PipetteFor accuracy when adding the solution to the iodine in the spotting tile

Stop ClockSo that solution can be added to iodine at regular time periods

Method.

Before the experiment begins, the water bath should be prepared at 0C, so that there is maximum accuracy in the experiment and to ensure that once the solution is placed in the water bath it as at the right temperature. Iodine should then be adding to the spotting tiles, so that at each 30 second interval the starch can immediately be placed onto the iodine. 2ml of starch is placed in the specimen tube. Next the specimen tube is placed in the iodine, so that once the amylase is added it can work at the correct temperature immediately, producing accurate results. 1ml of amylase is then added. The clock should be started as soon as the amylase is added and after the first 30 seconds, using the pipette a drop of the solution is added to the iodine in the spotting tray. The colour that the iodine changes to should be recorded. Keep recording the results every 30 seconds, until the iodine solution remains brown. The experiment should be repeated for accuracy and so that an average can be found....
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