Investigate the rate of reaction of amylase, when added to starch.

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Thomas Burton

Biology Coursework

Plan

In this experiment I will investigate the rate of reaction of amylase, when added to starch.

Variables

I will investigate how the rate of reaction increases with temperature.

I will keep these other factors constant, for fairer testing:

  • Concentration of Amylase
  • Concentration of Starch
  • pH

I will keep the concentrations constant by only using starch or amylase from the same container.

I will moniter the pH with universal indicator paper.

Prediction/Theory

I predict that the rate of reaction will be proportional to the temperature, until approximately 40°C.

This is because enzymes are essentially protein-based catalysts. They bind with the reactants very closely, thus reducing the activation energy level needed for the reaction to occur. The activation energy is the amount of energy that needs to be present, when the reactants meet for the reaction to occur.  The area where the reaction takes place is called the active site.  The protein molecules form a shape that the molecules of the other reactants must fit into, like a lock. When an enzyme is denatured (they are made from proteins), the activation site becomes warped, and so the reaction will not take place, as the molecules cannot properly meet there.

The proteins in the salivary amylase enzyme denature at around 40ºC, just over body temperature. The conditions in the mouth are not extreme, so the enzyme does not need to be as tough as others, which normally denature at around 50ºC instead.

This is a diagram of the reaction I will investigate;

This diagram was copied from:

This is the active site of the enzyme

This is the enzyme locking with the starch molecule and the reaction taking place. The starch molecules are broken down into two glucose molecules.

Reactions like this are very fast – thousands can happen every second.

Strategy

For this experiment I will need:

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2cm³ salivary amylase per test; 15cm³ per test; spotting tile; 500ml beaker; 1 test tube per test; spotting tile, 2 pipettes, a water heater with a thermostatically-controlled heating element, measuring cylinder, stopclock,  iodine with pipette, thermometer.

I will mix the starch and amylase together, then spot a sample of this on to some iodine every 30 seconds at different temperatures.

This is how I did the experiment:

I added the amylase and starch to the two test tubes, which I labelled. ...

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