Effect of temperature on the action of an enzyme

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Effect of temperature

on the action of an enzyme

Introduction

Enzymes are catalysts that speed up biochemical reactions. Most compounds found in cells are very stable and without enzymes would not react at any useful rate. Enzymes are proteins. Their molecular shape is important, because the enzyme needs to form a precise fit with the substrate – the molecule or molecules involved in the reaction. Only a small part of the enzyme makes contact with the substrate; this part is known as the active site.

The shape of the active site allows the substrate to fit perfectly, and to be held in place by temporary bonds, which form between the substrate and some of the R groups of the enzymes amino acids. This combined structure is termed the enzyme-substrate complex.

The enzyme may catalyse a reaction in which the substrate molecule is split into two or more molecules. Alternatively, it may catalyse the joining together of two molecules, as when making a dipeptide. Interaction between the R groups of the enzyme and the atoms of the substrate can break or encourage formation of, bonds in the substrate molecule, forming one, two or more products.

When the reaction is complete, the enzyme is unchanged by this process, so it is now available to receive another substrate molecule. The rate at which substrate molecules can bind to the enzymes active site, be formed into products and leave can be very fast.

In order to investigate the effect of temperature on the activity of diastase, I will test for starch using iodine solution to see how long it takes for the blue colour to cease when it is added to diastase solution kept in different temperatures.

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Variables

There are several variables that could affect the rate of reaction

Temperature:

I believe that with a higher temperature the higher rate of reaction up to a certain point. This is because as particles gain heat they move about much more, therefore thus increases the chance of a successful collision taking place. The reacting particles will collide more frequently, also with more energy; this will increase the rate of reaction.

This is the variable that I will be testing; all of the other variables will be kept constant.

pH:

pH is a measure of ...

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