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Enzymes, what are they?

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Enzymes, what are they? Enzymes are amazing molecules. They are produced by living cells, with each cell containing several hundred enzymes. They are extremely specific, generally reacting with only one substrate. They can speed up the rate of chemical reactions by as much as a million times, by lowering the activation energy without being used up or being unchanged. Within a cell, in the absence of enzymes, reactions would take place at too slow a rate to sustain life. To increase the rate of reactions, high temperatures would be necessary and this would be lethal to the cell. Activation energy without an enzyme, molecules react by randomly colliding, but energy has to be applied. For a reaction to take place molecules, known as substrates, have to collide with enough energy to break or form bonds, reacting products. The energy required to make substrates react is collide the activation energy. Binding for activity: Substrate molecules bind to the active site of an enzyme. The substrate molecules are usually much smaller than the enzymes. When the substrate binds to the enzyme, they slot neatly into the active site. This idea is called the lock and key model because the substrates seem to fit into the active site as a key fits into a lock. ...read more.


Place a ruler beside the cylinder. Cut the cylinder into discs 1mm thick. As the discs are cut, place them under water in a Petri dish; continue until you have approximately 60 discs. 2) After completing the above, assemble the apparatus, and then remove the rubber bung from the neck of the boiling tube. With a syringe, place into the boiling tube 5cm3 of buffer solution at pH 3.carfully add ten potato discs. Then, with another syringe, add 5cm3 of hydrogen peroxide into the boiling tube. 3) As soon as the hydrogen peroxide has been added, replace the bung, making sure it has an airtight seal. 4) As the reaction begins and oxygen is being produced the glass syringe should begin to fill up with the produced oxygen. Should be timing this experiment and measuring how much is produced every 20 seconds. 5) After this is completed, remove the bung and wash out the contents of the boiling tube and repeat the same experiment to reassure the accuracy and results. 6) Now carry out five further tests, each repeating twice with 10 new potato discs. Follow the same procedure as before but with buffer solutions of pH 4, 5,6,7,8 in turn making sure a clean syringe each time. Diagram Results: pH 3 Time (secs) ...read more.


19.25 220 8 14 15 22.5 20.25 240 8 14 15.5 24 21.25 260 8 15 16.5 25.5 22.25 280 8 16 18 26.5 23.25 300 8 17 19 17.5 24.4 Anomalies: As you can see there is a highlighted result which doesn't follow the same pattern that all the rest of the results do. This is an anomaly. The cause of this is unknown but the following things could be the reason(s) -The potato discs may have been cut unevenly, the syringes used may have been contaminated by being used in a previous experiment e.g. with a different buffer or the bung may not have been replaced after the hydrogen peroxide has been added. Evaluation: this experiment was very successful, excluding a small minority of anomalies. My prediction has been proven correct in the fact that the enzyme used, catalase, does indeed prefer more neutral conditions. The results follow a general pattern, the more acidic the solution is the less oxygen is going to be produced, and it is the same with high alkali solutions. To continue my investigation there is a lot of factors, which affect the rate of reaction, could that could change, for example the type of enzyme could change. An enzyme that prefers more acidic conditions could be used or the amount of time could be extended or diminished. John Murdoch Mr Tindall Enzyme investigation AS biology. I ...read more.

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