Effect of Different Temperatures on the Rate of an Enzyme Controlled Reaction

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Effect of different temperatures on the rate of an enzyme controlled reaction

I will place starch and amylase into five water baths which are at different temperatures, and record the time it takes to break down the starch in the solution.

Independent variables
The independent variable is what I am going to change in my experiment. In this case it is the temperature of the water in the five water baths- 10, 25, 40, 55, 70 degrees Celsius

Dependant variable
This is what will stay the same in my experiment in order for it to be a fair test. I record the time taken for the solution to go from black to colourless. Once colourless it proves there is starch present. I will use a stop clock to measure the time taken.

Control variables
This is what I will keep the same in the experiment so the test will be fair. I will keep the volume of starch and amylase the same in each part of the experiment. The test tubes will stay in the water for five minutes, and three drops of iodine will go into each test tube of starch.

Apparatus

5 Beakers
10 Test tubes
5 Thermometers
Starch
Amylase
Ice
Iodine
Kettle
Warm water
Dropping pipette
Graduated cylinder
1 Bunsen burner
Tripod
Heat proof mat
Gauze

Method

1. Collect all the needed apparatus needed or the experiment. 2. Set up one water bath at a time, starting with water bath 1. (10 degrees) 3. Fill the beaker up with cold water and add ice, and measure the temperature of the water. 4. Measure out 5cm3 of starch and 3 cm3 of amylase and place into two different test tubes; add three drops of iodine to the starch. 5. Set the test tubes into the water bath and leave for five minutes. Pour the starch and amylase into the water bath. 6. Start the clock.

7. Record in a table the times for the solution to turn from black to colourless. 8. Do the experiment for all the other temperatures, but adjust the water to the required temperature. 25 degrees- room temperature, 40 degrees, and 55 degrees add hot water and 70 degrees add boiled water from a kettle, if it exceeds required temperature decrease temperature with ice cubes. 9. Repeat the experiment for an average.

Prediction and justification

Enzymes are protein molecules found in living cells. When an enzyme combines with a substrate in its active, it will begin to break down that specific substrate. As the enzyme is a catalyst it will speed up the reaction but not take part in the reaction itself, they combine together forming an enzyme substrate complex. Due to the weakened state of the substrate its bonds are broken and new products are made. In my experiment the substrate will be the starch and the enzyme is amylase. The temperature of the solution affects the rate of reaction, the kinetic energy increases as the temperature does (as the temperature increases the molecules begin to collide faster causing more reactions). The faster the enzyme and substrate are moving the more they collide and the more of a chance there is of them colliding in the active site and producing an enzyme substrate complex.

In my experiment the speed of the reactions will vary according to each temperature. • In 10 degrees it will work slowest as the kinetic energy is working slowly due to the low temperature. • In the 25 degrees the reaction will still occur quite slowly but in 40 degrees it will turn colourless faster due to the increase in temperature and the colliding particles causing faster reactions. • In 55 degrees the solution will turn colourless but some enzymes may be denatured and will not work due to the hot temperature. In the 70 degrees water bath the solution will not turn colourless but remain will black as the enzymes will be denatured due to the very hot temperatures. When an enzyme is denatured it means the active sight changes so it cannot work. Influenced by temperatures, at a low temperature they work slowly, at a medium temperature they work faster,...
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