investigate how temperature and surface area affects the rate of reaction of the enzyme catalyse on its substrate hydrogen peroxide.

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Investigation

Aim

To investigate how temperature and surface area affects the rate of reaction of the enzyme catalyse on its substrate hydrogen peroxide.

Planning and investigational procedures

Background information

Enzymes are biological catalysts, which increase the rates of reactions. Enzymes increase the rate of reactions by lowering the activation energy needed for the reaction to start. The activation energy is the amount of energy needed, for molecules to react. Activation energy is required to break bonds and this causes molecules to react. When molecules collide they need a certain amount of energy to react and sometimes if enough activation energy is not present the molecules will collide but not react. The collisions theory is when molecules collide with each other to start a reaction. The molecules will only bounce off each other if the activation energy is not reached.

        The active site of an enzyme is where the reactions will take place or break down a substance. Only a certain enzyme will work on any substance this is called the substrate. The substrate of lipase is fats and for amylase it is starch. Only one substrate can be broken down by an enzyme, because the active site is different for each enzyme which means only one substance can fit. The ‘lock and key theory’ states that enzymes are like a lock where only one key can fit.

        Reactions in which large molecules are built up from smaller molecules are called anabolic. The opposite of anabolic reactions are called catabolic. These reactions are drawn below. . These reactions are drawn below.


        Enzymes can be affected by four factors; these factors are substrate concentration, enzyme concentration, temperature and pH.

        If you increase the concentration of an enzyme or a substrate this will therefore, increase the likeliness of a collision happening and a reaction occurring. However, there is a limit to the to the rate of reaction, if an enzyme concentration is increased from the same concentration of substrate then the rate of reaction will not increase this is because there are not enough substrate molecules for the enzymes to react with. .

        An increase in temperature will give more energy to both the substrate and the enzyme so they are more likely to react. The frequency of collisions with the right activation energy will increase also causing the rate of reaction to increase. The rate of increase is shown by a mathematical coefficient called Q10, the Q10 factor states that a ten-degree rise in temperature will result in the rate of reaction almost being doubled, however as the temperature begins to rise too high the enzymes will begin to denature. This means that the enzyme will no longer be able to hold its shape and the enzyme will begin to break resulting in the active sight and unique shape being lost and so it is unable to react with its substrate.

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        The optimum temperature for most enzymes is 40˚c, and after this they generally start to denature however, this is not always the case. The enzymes in the body have an optimum temperature and the body is adapted due to homeostasis to control this temperature so the enzymes are working at their best. Enzymes also have an optimum pH level where they work best at, and changes in this level can result in the denaturing of enzymes.

Hypothesis

I predict that a rise in temperature will coincide with a rise in the amount of bubbles up until 40˚c, and ...

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