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The effect of the concentration of the substrate on an enzyme.

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Introduction

Biology coursework Planning The investigation that I am going to do is a study into the effect of the concentration of the substrate on an enzyme. Enzymes: Enzymes are globular proteins, which act as biological catalysts. They lower the activation energy, the activation energy is the initial energy needed to break the bonds, to start the reaction. Amino acids with hydrophilic side chains are found on the outside on the enzyme, this makes the enzyme soluble, this is important as the amino acids that have hydrophobic side chains are found in the centre of the enzyme. However only a small number of amino acids are found on the active site. They are able to temporarily bind, using hydrogen bonds with the substrate molecules due to a region know as the active site. Because enzymes are proteins their activity can be affected by pH and temperature. The catalytic ability of enzymes depends on their three-dimensional shape; this is more commonly referred to as the enzymes tertiary structure. During an enzyme catalysed reaction a transition occurs during which the reactants together with the bound enzyme are referred to as the enzyme substrate complex. ...read more.

Middle

Up to the optimum temperature the rate increases geometrically with temperature (i.e. it's a curve, not a straight line). The rate increases because the enzyme and substrate molecules both have more kinetic energy so randomly collide more often, and also because more molecules have sufficient energy to overcome the (greatly reduced) activation energy. The increase in rate with temperature can be quantified as a Q10, which is the relative increase for a 10�C rise in temperature. Q10 is usually 2-3 for enzyme-catalysed reactions (i.e. the rate doubles every 10�C) and usually less than 2 for non-enzyme reactions. The rate is not zero at 0�C, so enzymes still work in the fridge (and food still goes off), but they work slowly. Enzymes can even work in ice, though the rate is extremely slow due to the very slow diffusion of enzyme and substrate molecules through the ice lattice. Above the optimum temperature the rate decreases as more and more of the enzyme molecules denature. The thermal energy breaks the hydrogen bonds holding the secondary and tertiary structure of the enzyme together, so the enzyme (and especially the active site) ...read more.

Conclusion

Collect the gas into another test tube full of water so that you can count the bubbles given off. Write your results down Diagram of my apparatus. Other factors. In my experiment it is important to keep all the other factors constant. I must make sure that the potato chips are the same size and the same mass. This will ensure that there is no increase in surface area. The temperature in which the experiment is undertaken must be the same. As I will do the experiment on the same afternoon the temperature should remain constant. The pH values must be the same; as I am using same substrate and enzyme source throughout the experiment this should also remain constant. Safety Factors: * We are using glass so we must be careful when handling it, to make sure that it is not smashed or knocked over. * We must be careful when handling the hydrogen peroxide as it can irritate the skin and could blind you if it came in contact with your eyes. * We are using knives to chop up the potatoes and we must take care when using these as the have sharp edges and may cut through skin. Results ...read more.

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