Enzyme Investigation - page 1
Keywords: Science Coursework Enzyme Investigation Chemistry Biology
By Jenny on 02/07/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 1 of 3 pages: 1 2 3
Enzyme Investigation
Introduction
What is an enzyme?
An enzyme is a biological catalyst (a catalyst is a chemical that lowers the activation energy needed for a reaction, speeding up the rate of reaction of the substance without being used up itself). An enzyme is a type of protein and there are lots of different types of enzyme because they are specific (each one will only work on one other sub-stance (substrate)). The place they work on is called the active site.
How do they work?
They work like chemical scissors cutting the links in the chemical chains of their sub-strate. They are specific because according to the Lock and Key Theory they work like a lock and key – the active site of each enzyme only fits one particular substrate so it can only work on that substrate.
What factors effect how enzymes work?
Temperature effects how well enzymes work – generally they work better the higher the temperature until they reach their optimum temperature at which they work best (fastest) and after that they are denatured (distorted) and can longer work because they no longer fit into the lock of their substrate.
pH also effects them in the same way – the higher the better until they reach their op-timum temperature after which they are denatured.
They are also effected by the concentration of enzymes and substrate - the more the quicker until there is the same amount of each.
I am going to investigate the effect of temperature on the rate of reaction of the enzyme amylase, which catalyses the break down of starch to sugar.
Prediction
I think that the rate of reaction will get faster the higher the temperature, until the en-zyme reaches an optimum temperature of 50ºC and after that it will be denatured and won’t work at all. This will happen because enzymes don’t work as well when they’re below their optimum temperature and then gradually get better as the temperature in-creases. However, after they’ve passed their optimum temperature they get distorted (denatured) and their active site doesn’t fit the substrate, so they don’t work at all.
Fair Testing
The factor that I will change is the temperature. The factors that I won’t change are: the amounts of everything used (e.g. the amounts of amylase, starch and iodine used and the amount of water in the water bath (beaker)), and the degree of clearness that we stop the stopwatch at.
List of Equipment
• Test tubes (2)
• Beaker
• Thermometers (2)
• Pipettes
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