The effect of Temperature on Enzymes

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The effect of Temperature on Enzymes

Aim: To investigate the effect of temperature on the breakdown of starch by amylase, and to find the optimum temperature for the reaction.

Research:

Enzymes are proteins that control vital biological processes. They often act as biological catalysts. They are made in cells. A catalyst is a chemical substance which speeds up a reaction but does not get used up during it. One enzyme molecule may be used several times over.

If starch is mixed with water it will break down very slowly into sugar, taking several years, however, in your saliva there is an enzyme called amylase which can break down starch to sugar in minutes or seconds.

A rise in temperature increases the rate of most chemical reactions and a fall in temperature will slow them down. In many cases a rise in 10¦ C will double the rate of reaction in a cell. This is particle theory. I am going to investigate the temperature at which reactions occur. An increase in temperature will result in a n increase in kinetic energy. Since the kinetic energy increases , the velocity of particles will also increase. Since the speed of particles increases, they should collide more often and therefore the speed of reaction increases. The particles will also have more energy thereby speeding up the reaction even more. It has been suggested that for every 10 degree rise in temperature, the speed of the reaction will double.

At low temperatures particles of reacting substances do not have much energy. However, when the substances are heated, the particles take in energy . This causes them to move faster and collide more often. The collisions have more energy, so more of them are successful. Therefor the rate of reaction increases.

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The more successful the collisions are the faster the reaction.

The same can be said for reactions controlled by enzymes, but because enzymes are proteins if the temperature exceeds 50¦ C the enzyme will be denatured and will no longer work. For this reason few cells can tolerate temperatures higher than approximately 45¦ C.

Enzymes are specific in the reactions they catalyse, much more so than inorganic catalysts. Normally, a given enzyme will catalyse only one reaction, or type reaction.

This shows how the shape of an enzyme molecule could be very important if it has to fit the substances ...

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