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Biology Coursework Planning

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					Biology Coursework Planning
                                                                      Samyar Siadati
Aim:
To see how pH affects the work of amylase

Prediction:
Amylase in the human body is found in slightly alkaline solutions. Therefore I expect
that it works best at pH 7-8 and its efficiency decreases as the pH changes either way.

Hypothesis:
I think the pH of the solution that amylase is to work on will affect the efficiency of
the enzyme. The reason is the lock & key hypothesis which claims that the enzymes
& substrates fit together to form the enzyme-substrate complex. Having a different pH
means a different concentration of Hydrogen ions or Hydroxyl ions. These ions can
disrupt the hydrogen bonds in the enzymes secondary structure (and to a much less
extend the tertiary and quaternary structure). So the bonds between the different
portions of amino acids will be disrupted, and therefore the shape of the enzyme
hence active site will be changed. This would mean that the enzyme and substrate
don’t fit and can’t from the enzyme-substrate complex. So the enzymes efficiency is
decreased. Amylase would break down starch into glucose, so by measuring the
concentration of glucose in the starch solution, the rate of enzyme action could be
measure and compared.

Other variables that might affect the result:
Temperature: Increase of temperature will increase the rate of reaction. Since
amylase denatures at 60 Celsius and that room temperature is much lower we should
not worry about the enzymes denaturing due to temperature. This will make our result
unreliable, so the temperature must be kept constant during the experiment. This can
easily controlled by making sure the room’s temperature doesn’t change throughout
the experiment. So if I use a thermometer, I can record the temperature every day, and
so if there a change in the temperature of the room, change the temperature to the
original temperature using the lab’s central heating.
Enzyme Concentration: An increase in enzyme concentration increases the rate of
reaction, in which would make our result unreliable. We must make sure the enzymes
used on the solutions all have the same concentration. By using all enzymes from the
same solution we can be sure that all enzyme solutions have the same concentrations.
Substrate Concentration: An increase in substrate concentration will need more
time for all the enzymes to act on the substrate. If we make sure all substrates come
from the same solution then we will know that they all have the same concentration.

Preliminary Test:
I will add 50 cm3 starch solution of concentration 0.5 mol.dm-3 and buffer solution of
pH 6(as I predict at pH 6 the reaction would have the slowest rate). Then add 50 cm3
amylase of conc. 0.5 mol. dm-3 to the starch solution. Then wait five minutes and
using Benedict’s solution find the concentration of glucose produced in the solution.
If the concentration of glucose is too high, I will decrease the conc. of amylase. If the
conc. is too low I will decrease the conc. of starch. I would do this till I get a
reasonable conc. of produced glucose. My suggested concentrations for amylase &
starch would be 0.5, 0.25, 0.1, 0.05 & 0.01.
Materials:
     Benedict’s Solution, used in test for glucose.
     Buffer Solution of pH 6, used to change pH.
     Buffer Solution of pH 7, used to change pH.
     Buffer Solution of pH 8, used to change pH.
     Buffer Solution of pH 9, used to change pH.
     Starch Solution, used as substrate.
     Amylase Solution, used as enzyme.
     Distilled Water, to dilute the solutions.

Equipment:
     Labels x 16, used to label the test tubes.
     Syringe 10cm3, used add amylase to the beaker.
     250 cm3 Beaker x 16, used to mix the amylase and starch.
     Pipette, used to add Benedict’s solution.
     Thermometer, used to be sure throughout the experiment the temperature of
      the room is constant.
     Bowl x 2, for water bath & cold water.
     Steering rod x 4, for mixing buffer & starch solution.
     Stop Clock, for the timings.
     Bunsen Burner & Tirpod, for warming water bath.

Procedure:
  1. Add starch solution to a 250 cm3 beaker.
  2. Add buffer solution of pH 6 to the starch solution.
  3. Mix gently with as steering rod so the pH is the same through out the solution.
      Make water bath ready.
  4. Add amylase solution to the beaker. Start the stop clock.
  5. After two minutes add Benedict’s solution to the beaker and place it in water
      bath.
  6. After five minutes take the beaker and place it in cold water. Wait until the
      beaker cools down.
  7. Using the colour of the solution record the concentration of glucose in the
      solution.
  8. Repeat this four times.
  9. Now do all these steps with buffer solutions of pH 7, 8 & 9.
  10. Find the mean conc. of glucose for each pH after 5 minutes(using SI units).
  11. Plot a graph of conc. of glucose against pH.
Safety Data:
                             Safety Data for Amylase
Toxicology: Sensitizer. May cause allergic respiratory reaction if inhaled.
Personal protection:
    Do not breathe dust.
    Avoid contact with skin.
    Wear suitable protective clothing.
    Wear suitable gloves.

                         Safety Data for Benedict’s solution

Risk phrases:
    Harmful by inhalation.
    Harmful in contact with skin.
    Harmful if swallowed.

Safety phrases:
    Wear suitable protective clothing.
    Wear suitable gloves.

                           Safety Data for Distilled Water
Safe handling:
No special protection needed in the laboratory.
Emergency:
Eye contact: Check that no extraneous material has entered the eye along with the
water.
Skin contact: Ignore.
If swallowed: Ignore.
Disposal:
 Pour down the sink.
Ethical Implications:
Amylase & Starch are gained from living organisms. Therefore I must be considerate
about how much is used. Using too much of these materials means wasting the lives
of living organisms. Also after the experiment the amylase cannot be re-used, so I
should try to not waste any of these, and also not use any in excess.

				
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posted:11/13/2011
language:English
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