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Investigating how concentration of enzyme affects the rate of an enzyme controlled reaction.

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Sarah Walker Investigating how concentration of enzyme affects the rate of an enzyme controlled reaction Background information Every enzyme is a protein; proteins are one of the most complicated of the organic molecules. Below is a simplified description of proteins, enzymes and the way they work. Proteins are made up of monomers (building blocks) called amino acids, these amino acids link together in different orders with special bonds called 'peptide bonds', when they are linked together they form a straight chain known as a polypeptide chain. This chain can be coiled or folded into shapes; either alpha helixes or beta pleated sheets, bonds link these together in different ways creating a unique structure, which in the case of enzymes is globular (roughly spherical). Enzymes are catalysts to organic reactions (they increase the speed of the reaction without changing it or themselves). Every enzyme catalyses a different reaction, this is because the enzyme has an area called the active site which also has a unique shape into which only one type of substrate (substance being reacted) fits. The enzyme breaks the substrate down into products, the diagram below demonstrates this: An enzyme can have its unique shape broken down by very high temperatures or extreme pH as these break the bonds which hold them together, this disfigures the active site of that particular enzyme and the substrate no longer fits; the reaction stops. ...read more.


I predict that the higher the enzyme concentration the higher the rate of reaction, this is because there are more enzymes per cm3 to which the substrate can attach and react with therefore more oxygen will produced in three minutes with the undiluted solution-100%. All results must be recorded in a table and later plotted into an appropriate graph using the averages of the three results at each enzyme concentration as diagrammed below. A table to show the volume of oxygen released in cm3 at varying enzyme concentration Solution Original 1 2 3 4 Time in seconds 100% 80% 40% 20% 10% 0 0.00 0.00 0.00 0.00 0.00 30 1.00 1.00 0.50 0.25 0.00 60 2.25 2.00 1.00 0.50 0.25 90 2.80 2.75 1.25 1.00 0.50 120 3.10 3.10 1.50 1.00 0.50 150 3.25 3.25 1.75 1.25 0.50 180 3.75 3.50 2.00 1.50 0.75 A graph to show the volume of oxygen released in cm3 at varying enzyme concentration The main trend of the graph agrees with my prediction and shows. The results were in general quite accurate although there were a few anomalous results- there was an overlap of results between the 80% and 100% concentration at points 1, 2 and 3 this could be due to the concentrations being similar, contaminations during some point of the experiment, variations in room temperature or inaccurate reading of results. ...read more.


c) Take 5cm3 of solution 1 and mix 5cm3 of water in a mixing pot-40% concentration (solution 2) d) Take 5cm3 of solution 2 and mix 5cm3 of water in a mixing pot-20% concentration (solution 3) e) Take 5cm3 of solution 2 and mix 5cm3 of water in a mixing pot-10% concentration (solution 4) 2. Fill a 1000cm3 beaker 3/4 full with water. Fill a 10 cm3 measuring cylinder to the brim with water and place your thumb over the top, invert the measuring cylinder taking care to prevent any loss of water and position in the beaker so that the mouth of the cylinder is below the waters surface. 3. Take the delivery tube and place one end under the lip of the measuring cylinder. 4. Place 3cm3 of the original solution in a conical flask, place in the waterbath and allow to acclimatise to room temperature for 10 minutes. 5. Place 3cm3 of hydrogen peroxide in a 10cm3 syringe and insert through the bung of the conical flask alongside the delivery tube, insert the hydrogen peroxide making sure the bung is tightly on so no gas escapes. Start the stopclock at the same time and measure the amount of gas produced in the measuring cylinder in a 3 minute time period. 6. Repeat twice more. 7. Repeat this process for each of the following solutions: 80%, 40%, 20%, and 10%. ...read more.

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