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Investigate the effect of sucrase concentration on the rate of hydrolysis of sucrose.

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Andrew Mackay 12 E As Biology Coursework 2002 Investigate the effect of sucrase concentration on the rate of hydrolysis of sucrose. Skill P - Planning Hypothesis - The digestion of sucrose into glucose and fructose is carried out by the presence of the enzyme Sucrase. The activity of the enzyme will be greatest at its optimum temperature since at this temperature the enzyme's tertiary structure will be correct to allow the formation of the substrate-enzyme complex quickly and efficiently. This should be at 37�C (body temperature), which is the temperature of the ileum where Sucrase is secreted and naturally functions. The first thing to say about enzymes is that they are proteins and they are found in all types of organisms from humans to viruses. They function in the body as catalysts. In other words they speed up the rate of chemical reactions in the body. Enzymes actually accelerate chemical reactions by a factor of about 1 million. Enzymes are organic catalysts. Without enzymes the metabolism of an organism would be too slow for the organism to survive. The word enzyme actually means "in yeast" as they were first discovered in these micro-organisms. Enzymes are found inside cells (intracellular) and outside cells (extra cellular). Intracellular enzymes are for example, those that control metabolism while extra cellular enzymes are for example, gut digestive juices and the enzymes secreted by bacteria, which digest their food outside the body then reabsorb the products. Enzymes work on particular organic chemicals, these are called substrates. ...read more.


The rate of a reaction will increase with an increase in temperature until the optimum temperature is reached. At temperatures greater than optimum, the kinetic movement of molecules in the enzyme are too great to hold it together, eventually denaturing the enzyme. These two different enzyme reactions show how temperature will affect each differently. Lock and key theory and induced fit model An enzyme molecule is globular and very large but only a small part of it, the active site, is involved in the reaction. This animation shows how the shape of the active site matches that of the substrate molecule. The substrate molecule fits into the active site and is held there until the reaction is complete. The product is then released and the enzyme is once again ready to take part in the reaction. This is known as the lock and key hypothesis. The active site has a distinct shape, rather like a lock. Just as only the right 'key' will fit a lock, so only the right substrate has the right shape to fit into the active site. Induced-Fit Model of Enzyme catalysis Metabolism is defined as all the chemical processes inside the cells of a living organism. These could be for building up, maintenance or breaking down of living tissue. Reactions in cells tend to occur spontaneously to produce an end product .The reactants are stable before the reactions take place and must be destabilised by breaking bonds in the reactants. ...read more.


To avoid this I used a colour chart and chose an exact colour that was just different enough from the starting colour. As well as this the final colour was defined. Results : my results from then on were much more reliable and the average was easier to plot on a graph drawing my expected curve. The first colour change was a loss of the base pink colour and the final colour change is a measurable blue. Throughout all these preliminary experiments and the final one all laboratory safety precautions will be observed. To check the reliability of my results I will take a mean average of all 3 experiments I finally did. Using the mean of all the experiments I then will work out the standard deviation of the primary colour change and the final colour change. On the graphs the X axis is numbered 1-6, this corresponds to the Sucrase Concentration 0.0%-2.5%. Below is the preliminary experiment graph for primary colour change at 0-5% solution. Experiment Solution (molar) Time for final colour change 1 0 2 1 30 3 2 20 4 3 10 5 4 4 6 5 0.5 The line slopes down as the reaction time decreases in relation to the concentration. This was the graph of the preliminary experiment after making the changes due to evidence from preliminary experiment 1 and 2. Prediction: I predict that the higher the concentration the faster the reaction due to induced fit and lock and key hypothesis. ...read more.

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