• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16
  17. 17
    17
  18. 18
    18
  19. 19
    19
  20. 20
    20
  21. 21
    21
  22. 22
    22

Investigating the Rate of Reaction of the Enzyme Amylase on starch

Extracts from this document...

Introduction

Individual Investigation: Investigating the Rate of Reaction of the Enzyme Amylase on starch By Osman Khan Lee 13 Aim The aim of my investigation is to see what factors affect the rate of reaction of the enzyme amylase on starch. These factors will be temperature, effect of an inhibitor, the enzyme concentration and the substrate concentration. Starch Starch is a mixture of amylose and amylopectin. Amylose is made up of many monosaccharides units of ?- glucose molecules, joined by alpha 1,4 glycosidic bonds. This builds up a long unbranched chain of glucose molecules, which then coils around itself into a helical structure- rather like a spring. Amylopectin is similar to amylose but also has alpha 1,6 glycosidic bonds, which makes the chains branched. The mixture of these two molecules is starch and is used as energy storage in plants. 1 Left: Diagram showing the structure of amylopectin Right: Diagram showing the structure of amylose The result of the enzyme amylase on starch is the conversion to maltose. This result can be detected by using potassium iodide. If no starch is present the colour of the solution will turn orange. In the presence of starch the potassium iodide turns a dark blue/black colour. As I said earlier the starch molecules curl up into structures like a spring. The hole, which runs down the middle of this spiral, is the same size and shape of the potassium iodide molecule, so the molecules can fit into the spiral. This is what gives the intense blue/black colour when potassium iodide is mixed with a solution of starch. Due to the colour change of the solution, the transmission of light through the solution will vary. Therefore, using a colorimeter, I will be able to detect how the transmission of light through the sample changes. This can then be interpreted on a calibration curve of known starch concentrations, enabling me to find out how much starch is left after a given time period. ...read more.

Middle

I have decided these volumes based on previous research, in which I investigated the action of copper sulphate on catalase. I therefore expect the reaction to occur somewhat the same, with small concentrations having large effects on the output of the enzyme. Once again my standard solutions for this variable will be amylase 3% and starch 1%. As there are 90 readings in total and a cuvette volume of 4cm3, I will require about 360cm3 total solution. I therefore require approximately 180cm3 of amylase and 180cm3 of starch. Amylase 4% 4% of 180 = 7.2 Therefore I must add 7.2g of amylase powder to 180cm3 of distilled water to make a 4% amylase solution As the reactants are being put in as 1cm3 amylase: 1cm3 starch I will require 180cm3 of starch solution. 1% starch 1% of 180 = 1.8 Therefore I must add 1.8g of starch powder to 180cm3 of distilled water to make a 1% starch solution To make the copper sulphate concentrations I will make a total of 10cm3 copper sulphate/water solution. 0.1% Copper Sulphate 0.1% of 10 = 0.01g Therefore I must add 0.01g of copper sulphate to 10cm3 of distilled water to make a 0.1% copper sulphate solution 0.2% Copper Sulphate 0.2% of 10 = 0.02 Therefore I must add 0.02g of copper sulphate to 10cm3 of distilled water to make a 0.2% copper sulphate solution 0.3% Copper Sulphate 0.3% of 10 = 0.03 Therefore I must add 0.03g of copper sulphate to 10cm3 of distilled water to make a 0.3% copper sulphate solution 0.4% Copper Sulphate 0.4% of 10 = 0.04 Therefore I must add 0.04g of copper sulphate to 10cm3 of distilled water to make a 0.4% copper sulphate solution 0.5% Copper Sulphate 0.5% of 10 = 0.05 Therefore I must add 0.05g of copper sulphate to 10cm3 of distilled water to make a 0.5% copper sulphate solution Scientific Theory An enzyme can be defined as a biological catalyst and like any other it is affected by the conditions it is in. ...read more.

Conclusion

The order of reaction is therefore 2. This means that the rate is directly proportional to the concentration of (CH3)3CBr, but the concentration of OH- has no effect on the rate of the reaction. Why is this so? The effect of OH- has been found to not affect the rate of reaction because it occurs in two stages. In the first stage, which is shown in step 1, the C-Br bond breaks heterolyticaly. This therefore means the OH- concentration doesn't affect on the rate of this bond breaking. The second part of the reaction, shown in step 2, is the reaction of the carbocation with the OH-. This stage of the reaction occurs very quickly, like most nucleophilic reactions. Stage 1, however, is slower than this and so the rate depends only on the concentration of (CH3)3CBr. Step 1 is therefore called the rate-determining step. The rate equation for this reaction is therefore Rate = k [(CH3)3CBr] This shows that the rate equation, as stated earlier, cannot be found just by looking at an overall balanced equation. Instead the mechanism of the reaction must be found. In an enzyme-catalysed reaction, the enzyme uses up the substrate. Therefore, to find the order or reaction of that substrate, its concentration must be kept the same. This can be done by just working out the initial rate of the reaction- i.e. when the substrate concentration exceeds the enzyme concentration. Therefore, after doing my practical, I will be able to analyse the results and see what order of reaction the reactants are. 1 Diagram taken from Biology 1 Advanced Sciences page 26 by Mary Jones, Richard Fosbery and Dennis Taylor 2 Diagram taken from Biology 1 Advanced Sciences page 42 by Mary Jones, Richard Fosbery and Dennis Taylor Diagram taken from Salters Advanced Chemistry: Chemical Ideas 10.2 page 225 4 Diagram taken from Biology 1 Advanced Sciences page 48 by Mary Jones, Richard Fosbery and Dennis Taylor 5 Example taken from Salters Advanced Chemistry: Chemical Ideas 10.3 page 235 Osman Khan Lee 13 Page 1 of 22 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    How does the concentration of enzymes affect the breakdown of starch by a-amylase in ...

    4 star(s)

    Taking for example a pure enzyme solution, adding a substrate into this solution means the ratio between the enzyme molecules and the substrate molecules is fairly small, which means there are a small number of substrate molecules for each enzyme molecule.

  2. Marked by a teacher

    effect of concentration of copper sulphate on the action of amylase to break down ...

    4 star(s)

    There are three levels of structure of enzyme; the primary, secondary and tertiary structure. The primary structure is the order and type of amino acids that made up the chains. The secondary structure is the folding of the chains into either beta sheets or helix.

  1. Marked by a teacher

    Investigating the effect of temperature on the breakdown of starch by amylase.

    set up a tile with iodine drops already on it, in the depressions on the tile. A drop of the solution collected during the experiment could then simply be added to this and the colour noted. I also decided not to note the index of concentration, as this was impractical,

  2. Investigation of the effect of adding different concentrations of NaCl to an enzyme-substrate (amylase-starch) ...

    This can either be reversible, where by the inhibitor eventually leaves and the active site is restored, or it could be irreversible. Irreversible inhibition occurs when the inhibitor either permanently attaches to or heavily denatures the enzyme, resulting in the tertiary structure becoming unrestorable.

  1. The effect of Copper Sulphate concentration on Catalase activity on Hydrogen Peroxide.

    I will now move onto focusing on the single graphs, and I shall be referring to the second part of my prediction. I had predicted that the curves would be reaching a plateau if the reaction had continued for a long enough period of time.

  2. How does pH affect the Denaturation of enzymes Starch and Amylase.

    It did not react as the pH used would have altered the structure of hydrogen bonds in the alpha amylase, and therefore denatured the enzyme. PH levels are an important factor which enzymes require to be at the optimum for each condition for each enzyme to perform at it's quickest.

  1. Exploring the Effects of Copper Sulphate as an Inhibitor on the Enzyme Amylase

    This regulation can be controlled by something called an inhibitor. Inhibitors work by preventing the substrate from combining with the enzyme. There are different types of inhibiton - competitive, non-competitive.The inhibitor in this is experiment is copper sulphate. Copper Sulphate is a heavy metal that reduces the effectiveness of Amylase by inhibiting it.

  2. Investigation into the varies stages of mitosis

    There is a difference between each individual result because each commercial slide that was looked at was individual with different individual cells therefore no slide will be identical. Misidentification may have been helped with a better resolution microscope as the light microscope has limitations although it should be adequate to study the stages of mitosis.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work