Enzymes are protein cells and they are found in the gut. They help to break down the food you eat. Enzymes are produced by living cells and they speed up reactions because they are biological catalysts. If we did not have enzymes, the reactions in our cells would be too slow to keep us alive. This means that they are extremely important for our survival. The properties of enzymes are:
⋆ They can be used many times, because they can speed up
reactions without using up any of themselves.
⋆ Their presence does not affect the end product.
⋆ They only need a small effort to change a large amount of substrate.
⋆ Enzymes are very specific and usually only speed up a single reaction.
⋆ Their rate of activity depends on the PH of the substance, the temperature of the substance and the concentration of both the substance and the enzyme.
An enzyme fuses with its substrate and this makes an enzyme-substrate complex. Once this reaction has occurred, the complex will break up into the enzyme and the products. After all of this, the enzyme is not changed and can repeat the reaction again.
Enzymes play a major part in the ‘lock and key’ idea. This is when a substrate molecule collides with a molecule of the correct enzyme. It will then fit or ‘lock’ into the active site, which is now free for the reaction to happen again. The active site of each enzyme is specific to fit with just one type of substrate.
The three main digestive enzymes in the body are; protease, which comes from the stomach, the pancreas and the small intestine. It works on proteins and the products of its digestion are amino acids. The next main enzyme is carbohydrase, which is in saliva, the pancreas and the small intestine. The product of digestion is glucose. The last enzyme is lipase. It is found in the pancreas and the small intestine, it works on fats and produces fatty acids and glycerol. Lipase works best at a pH of 7-8.
My aim with this experiment is to discover how altering the temperature affects how well lipase works.
I predict that as the temperature increases, the time taken for the solution to turn milky will decrease, but this is only true up to 40%. This is because as you give enzymes more energy, they move faster and as they move faster they are more likely to collide. More collisions mean more reactions, so meaning that more fatty acids and glycerol are produced. The quicker the fatty acids are made, the quicker the pH will change and the quicker phenolpthalien will change from pink to clear. For example, Then over 40º, enzymes denature, because it is too hot for them to survive, and at lower temperatures enzymes move less and so, less collisions occur, meaning slower reactions, because when the temperature is higher, the particles in the mixture vibrate faster, increasing their energy and increasing their collisions because they are moving faster and this causes them to collide more, also producing an increased amount of energy. So, when the temperature is lower, the opposite happens and the particles vibrate less and move less. As they move less, fewer collisions occur and they produce less energy. Also, if the temperature is greater the time will be shorter, because as there are more collisions occurring and more energy is being produced, it will not take as long for the enough collisions to occur for the mixture to turn from pink to clear, and vice versa. If the temperature is lower, it will take more time for the mixture to change colour, because there will not be as many collisions happening at once, so it will take longer.
I will be doing several things to ensure that this experiment is a fair test. Firstly I will be accurately measuring all of the components in my mixture. I will also be making sure that each temperature is correct in accordance with my table by using a water bath. Another thing I am going to do...
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