The Effect of Temperature on the Action of Amylase on Starch
AIM: I am trying to find out how the temperature affects the action of
amylase on starch.
Enzymes are composed of amino acids, they act as catalysts to regulate
the speed of chemical reactions in living organisms. Hydrolytic
enzymes speed up reactions; amylase
is one of these. Enzymes regulate
the speed of chemical reactions
by building up or breaking down
substances, this is done by the 'lock and key' sequence. All enzymes
have their own specific shape- like all locks, like a lock it has a
specific 'key' that fits into the specific substance, that is
exclusive to its appropriate enzyme. Enzymes have an optimum
temperature and pH to work in, when the temperature is too high for an
enzyme it will become deformed and will cease to function, but if
temperature is too low it will function but at a low rate to a point
where again it will cease to function; until the heat has been
is a carbohydrate made up of a chain of glucose. Starch is an
insoluble, complex molecule and is titled a polysaccharide. A
substance called Iodine detects starch. If Starch is present it turns
a blue/black color, if none is present is stays an orange/red color.
Starch rich foods include: bread, pasta etc.
Amylase is a type of enzyme. It specifically breaks down Starch and
turns it into maltose, a disaccharide. It is secreted in the salivary
Hypothesis: I think at 0 C the amylase will be defective because there
is no energy for it to function. When the temperature is increased the
amylase will begin to breakdown the starch but very slowly. At its
optimum temperature (40°C). It will work at a very high rate and
almost all starch will be broken down. When the temperature is
increased to 50°C or above the amylase will become deformed and cease
At 0°C there is no heat to supply energy to the enzyme and substrate
so they move nor react.
At 10°C there is a little energy thus allowing the enzymes and
substrates to move a little. Some react but many take very long due to
the low supply of energy.
Very close to optimum temperature and is still at quite at low rate of
At its optimum the enzymes and substrate are working at its highest
Though the enzymes and substrates are working a lot quicker but the
enzymes have become deformed because of high temperature. Some may
still be active.
Same as 50°C except all are deformed and extremely fatter.
Safety: Working with a temperature of 60°C if you are not careful this
can scold you.
Working with a water bath be careful the water and electricity do not
Working with glassware - do not break and leave injuries can occur.
Independent - Temperature
Dependent - Rate of Enzyme
Controlled - Amount of amylase
- Concentration of amylase
- Amount of starch
- Concentration of starch
- Water level in bath
- Amount of iodine (3 drops)
- pH level in water bath
Fair Test - Do not experiment three times and find an
average from results.
- See variables: Controlled
Measurement - Range of measurements - 0 to 60°C
- Interval - Rise by 10°C
Equipment List - Thermometer (measures temperature)
- Measuring Cylinder (measures volume)
- Stop watches (measures time)
- Water Bath
- Test Tube
- White Tile
- Universal Indicator
This is an experiment I have done previous experiment:-
Time taken for
Starch to Disappear (Mins)
Less than a min.
I am not using 10ml of starch to 1ml amylase because it takes far too
long to breakdown.
I am not using 3ml of starch to 1ml of amylase because it breaks down
The best choice would be to use 5ml of starch to 1ml of amylase,
however because I am taking drops out to test whether the solution has
starch I am going to double this to 10ml starch and 2ml amylase so it
does not run out.
Two different measuring cylinders will be used for measuring starch
Step 1 Gather all equipment (see equipment list)
Step 2 Put 3 drops of iodine in each groove of white tile.
Step 3 Put 10mls of starch in one test tube and 2 mils of amylase in
Step 4 Put both in a water bath till they have reached a required
Step 5 Mix the amylase and starch in one test tube.
Step 6 Take a sample of the mixture using the pipit and drop in iodine
every 20 seconds checking to see whether starch is present.
Step 7 Do experiment (steps 1-6) three times for this particular
Step 8 Do steps 1 - 7 for each temperature.
Table of Results
Amount of Starch (ml)
Amount of Amylase (ml)
Time taken for starch to disappear
Rate of Reaction
In my results table, it is noted that when the temperature rises, the
rate of reaction increases very quickly but when the temperature gets
40°C (optimum temperature), the rate of reaction declines rapidly. At
0°C no reaction takes place after 15 minutes. Due to past knowledge of
enzymes I know they cease to function so it is assumed there is not
reaction. At 40°C the rate of reaction is at its best with a reaction
rate of 0.5000. It then drops dramatically to 0.0167 at a temperature
of 50°C. At 60°C the same result as 0°C has occurred due to the
deformation by the high temperature. On my graph the line of best fit
has a gradually rising slope at 40°C plus. The rate of reaction
decline and a steep fall is seen from 40°C (0.800) to 60°C (0.0000).
This is because:
· The benefic energy allows enzymes and substrates in the 'lock and
· 40°C is the optimum temperature because it is closed to body
temperature (37°C) where amylase is found. This is why the rate of
reaction is at its peak.
· Though more heat gives more energy any temperature above 40°C
(optimum) causes the amylase to become deformed.
Also see scientific explanation.
My experiment went exactly to plan and I had not real problem with it.
I feel my best results were at 0°C, 10°C, 40°C and 60°C because all
three results were the same so I presume they were most accurate e.g.
0°C results were 00, 00, 00 and 40°C results were 20, 20, 20. The
results of 0°C and 60°C were assumed infinite (00) after 15 minutes
however, I am not sure if it was enough to assume infinite. May be
another 15 minutes would have helped me to confirm the results. I
still believe they were correct because at 0°C there is no energy and
t 60°C the enzyme active site is denatured disabling the substrate
A high percentage of the points on my graph was close to the line of
best fit. The anomalous result was 20°C. It is rear room temperature
yet the results from this water both were very unstable. Reasons for
this may include contaminations to solution. pH may have changed or an
inaccurate amount of substance (amylase and starch).