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Coursework Biology EssayBiology coursework Substrate specificity in yeast AIM To find out which substratum (glucose, starch, maltose, sucrose or lactose), does yeast, the organism containing the enzyme, breaks down the quickest. Introduction Usually, every enzyme has a specific substrate that is what we call the lock and key theory. We can try the answer of an enzyme with different substrates and this enzyme will just work well with one of those substrates. One type of reaction catalyzed by enzymes is anaerobic respiration. (fermentation), made by yeast that uses a sugar as a substrate. This reaction will produce CO2 and energy.Measuring how much CO2 the reaction produces we could know how well the enzyme is working with a substrate, checking thus its specificity. Materials 5 Ignition tubes Pipette Glucose Maltose Sucrose Lactose Yeast Cotton wool Test tubes Stop watch Ruler Variables sovereign variable substrate (glucose, starch, maltose, lactose, sucrose), enzyme (yeast), vo lume of substrate, volume of enzyme. Dependent volume of CO2 released (measured in mm) Controlled variables Temperature, pressure, time.Method 1- Fill 5 ignition tubes, fractional with yeast (2.0 ml) and half with each corresponding substrate (2.0 ml), using a pipette. 2- Quickly after the mixture is done, place the ignition tubes upside down in a screen tube, helping yourself with a pen. 3- Start the stop watch once the ignition tube is upside down in the test tube, and measure the space left-hand(a) (this will be time 0) 4- Place some cotton wool on the top of each test tube in order to close off oxygen, and therefore, for anaerobic respiration to occur.5- Prepare one mixture with the yeast (enzyme), and with water, to act as a control. Treat the control in the same way you earn done it with the samples. 6- As anaerobic respiration occurs, CO2 is released displacing the mixture of yeast and substrate into the test tube. Measure the amount of CO2 released during 20 minutes, ta king a reading of the empty space inside the ignition tube every 5 minutes. 7- Repeat the experiment 3 times for statistical purposes.