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Aim:
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I am investigating the effect of temperature on the enzyme amylase and the breakdown of starch. I want to find the optimum temperature the enzymes work ay.
I will keep the same volumes of amylase and starch but always change the temperature of the starch and amylase.
Prediction:
Since enzymes are proteins, I predict that they will denature if the temperature exceeds 50 degrees. It will no longer work. Above 50 degrees the shape of an enzymes is damaged.
An enzyme has an active site, which has a unique shape into which only a substrate of the exact same unique shape can fit.
The active side will change after the temperature exceeds 50 degrees and the enzyme can no longer combine with the substances. I predict that the breakdown of starch will be quicker when the temperature is increased until it exceeds 50 degrees.
This happens because more kinetic energy is given to the enzymes
An increase in temperature means an increase in kinetic energy. Since the kinetic energy increases, the speed of particles will also increase. Since the speed of particles increases, they should collide more often and therefore the speed of reaction increases.
The more successful the collisions are the faster the reaction. But since enzymes are proteins and if the temperature exceeds 50 degrees the bonds inside the enzyme, will break and the enzyme will be denatured and will no longer work.
enzyme at 20°C
enzyme at 70°C
substrate
substrate
Apparatus:
I have decided to use the following equipment:
· Bunsen burner
· Water bath
· Stopwatch
· Iodine
· Measuring cylinder
· Test tubes
· Thermometer
· Pipette
· Spotting tile
· Amylase
· Starch
Method:
- set water bath to the temperature wanted
- measure 8 ml of starch into test tube using a measuring cylinder
- pour 8 ml of amylase into another test tube
- put both test tubes in water bath
- use thermometer to check temperature of the water
- put 2 drops of iodine into the spotting tiles (when starch is present the colour of iodine changed to dark blue)
- when wanted temperature is reached, mix amylase with starch and start the stopwatch.
- Stir mixture
- Remove 2 drops of the solution every 30 seconds
- Record time until solution does not change the colour of iodine anymore
- Repeat at different temperatures
Results:
after having repeated the experiment several times, I came to the result that the enzyme Amylase works best in 35 degrees.
To show this more precisely, I will put my results in a table below.
Time in seconds
Temp in degrees
30
60
90
120
150
180
210
240
270
300
30
X
X
X
X
35
X
X
38
X
X
X
X
40
X
X
X
X
50
X
X
X
X
X
X
60
X
X
X
X
X
X
X
X
70
X
X
X
X
X
X
X
X
X
X
As you can see, the Amylase takes only 60 seconds at a temperature of 35 degrees to break down the starch, whereas above 40 degrees it takes longer, because the enzyme begins to denature and starch isn't broken down easily.
At 70 degrees, the enzyme has completely denatured and the active site can no longer combine with the starch.
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