Investigating The Effect Of Temperature On Plant and Fungal Amylases

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Investigating The Effect Of Temperature On Plant and Fungal Amylases

Enzymes are biological catalysts responsible for catalysing metabolic reactions. They increase the rate of reaction. Amylase is an enzyme which catalyses the hydrolysis of poly/disaccharides into monosaccharides.

Temperature affects how quickly the enzyme catalyses the breaking up of the substrate (what the enzyme is breaking down). It increases the rate of reaction (amount of substrate which is converted to product per unit time). The reason for this is because at higher temperatures the molecules have increased kinetic energy than at lower temperatures. With increased energy, they are more likely to bump into each other and it is more likely that the substrate and active site will collide and react to produce a product. When the molecules do collide, there is increased chance they will overcome the activation energy barrier. This is the energy needed to start the reaction.

At very high temperatures the enzyme ceases to work. This is because enzymes are proteins and become denatured at high temperatures. The high temperatures cause the hydrogen bonds and hydrophobic interactions to break, which changes the shape of the enzyme. At a different shape the enzyme can no longer hold the substrate. As the temperature increases even more the whole protein becomes completely denatured. The reaction stops.

At the optimum temperature, the maximum rate of reaction occurs, the maximum amount of product produced per unit time. Plant enzymes have an optimum temperature of around 25 degrees C. Some other plant enzymes can withstand even higher temperatures. Enzymes in fungi have very high optimum temperatures.

Rises of 10 degrees approximately double the rate of reaction until the optimum temperature is reached.

Enzymes have a particular shape. The active site of the enzyme is designed to enable the substrate to fit in exactly. In this investigation the substrate is starch. Lining the active site are amino acids, which form temporary bonds with the starch molecule, as it slots into the active site. A hydrolysis reaction occurs between the enzyme and substrate, which splits the starch molecule into smaller molecules of monosaccharide.
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Hypothesis

I predict that as the temperature increases, the rate of reaction will increase. This is because the molecules have more kinetic energy and the chances of the enzyme and substrate colliding will be greatly increased. At lower temperatures, the molecules have less kinetic energy and there is decreased chance that enzyme and substrate will collide and react. When the molecules have more energy there is more chance they are able to overcome the activation energy barrier and form a product.

I predict that at an increase of 10 degrees, the rate will double. This ...

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