Investigating How the Rate of a Reaction Involving Amylase Differs as the Temperature Changes

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Investigating How the Rate of a Reaction Involving Amylase Differs as the Temperature Changes

Planning:

Our aim is to observe what effect varying the temperature will have on

the rate of a reaction involving an enzyme.

I predict that as the temperature increases, from 5oC, the rate of a

reaction will increase till it reaches the optimum rate of reaction.

After this the rate of reaction will decrease. This is due to the

structural format of the enzyme. An enzyme is a globular protein

structure which has a very specific primary structure and because of

that can fold up into a very specific shape, if shape or amino acid is

missing or replaced by another in primary structure the enzyme cannot

function. As the temperature increases the enzyme will have more

energy so will be able to collide more often with a substrate and

bind. This will increase until optimum temperature which is around 37OC

- 40oC. After it has reached this temperature the heat energy causes

the molecules to vibrate because of the kinetic energy from the heat,

this will cause bonds to break particularly hydrogen bonds which are

not the strongest bonds made. This will therefore change the globular

protein shape, and so the active site, therefore no substrate will fit

into the site and the enzyme is no longer useful and is called

denatured.

We have chosen to vary the temperature, there are three other

variables to change and see what effect they will have on an enzyme,

therefore all other variables need to be controlled. We will need to

control the pH because the pH scale represents the percentage of

hydrogen ions in the solution; these H+ will react with globular

protein and make hydrogen bonds with its side chains. Therefore each

molecule has its own pH it works best at. At the optimum pH the active

site of an enzyme will accept the substrate. Amylases’ optimum pH is

around 10. Another variable needed to be controlled is the

concentration of the substrate. We will need to use a set

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