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My aim in this investigation is to investigate how the concentration of amylase affects its rate of reaction with starch.

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Biology Investigation (Coursework)- GCSE Aim- My aim in this investigation is to investigate how the concentration of amylase affects its rate of reaction with starch. Introduction- My investigations main topic is enzymes and how they break up foods, I will be mainly concentrating on how concentration affects the reaction of amylase on starch and how fast this reaction occurs. Enzymes are biological catalysts. They speed up the chemical reactions, which go on inside living things. What Are Enzymes- Enzymes are protein molecules, made by living cells, which act as catalysts and speed up the rate of metabolic reactions, by lowering the activation energy required. In the absence of enzymes, the anabolic and catabolic reactions that make up metabolism would be far too slow to maintain life. The reactions occurring inside our living cells are called metabolism. Some of the reactions build things up (anabolism), for example- glucose is built up into glycogen for storage, and amino acids are linked together to form protein for bodybuilding. Other reactions break things down (catabolism), for example- glucose is broken down into carbon dioxide and water with the transfer of energy. Enzymes enable all these reactions to occur. Types Of Enzymes- Enzymes come in two main parts, breaker enzymes and builder enzymes. - Breaker enzyme, these break down large insoluble molecules into smaller soluble materials. - Builder enzyme, these are small molecules joined together to form large molecules. These speed up reactions. Enzymes work on substances called substrates; this takes place on part of a surface called the active site. Breaker enzyme- Builder enzyme- Enzymes are produced inside our living cells. After they are formed, the enzyme may leave the cell and do its job on the outside. Theses enzymes are called extracellular enzymes. These include the digestive enzymes, which break down food substances in our gut. Other enzymes do their job inside the cell it was formed in. ...read more.


Most enzymes work fastest at a pH of approximately 7 (neutral condition). PH changes can affect the structure of an enzyme molecule and this affects its ability to bind and react on its substrate. Substrate Concentration- The more concentrated the substrate, the quicker the reaction. This is true for chemical reactions in general. In enzyme-mediated reactions, however, there is a second issue. There are a limited number of enzyme molecules available. Each one is occupied for a while each times it binds the substrate and catalyses the reaction. There comes a point when each enzyme molecule is constantly occupied. As soon as one product molecule leaves, another substrate molecule binds. Adding more substrate cannot make the reaction faster. So, overall as substrate concentration increases, rate of reaction increases at first. As concentration rises further, rate levels off at a maximum value. Enzyme Concentration- The more enzymes there are, the faster the reaction. More enzyme molecules means more frequent enzyme-substrate collisions, so more product is made in given time. This is the main factor affecting my investigation. Enzyme Inhibitors- Inhibitors are molecules, which take no part in a reaction, but make the enzyme less effective. They reduce the rate of reaction. Some inhibitors are a normal part of the working cell. Others are potentially dangerous foreign molecules. Inhibitors are classified as either reversible or irreversible. Irreversible inhibitors bind more or less permanently to same part of the enzyme. The enzyme's shape is changed, and it loses its activity. Reversible inhibitors are divided into competitive and non-competitive inhibitors, depending on how they bind. Competitive inhibitors bind reversibly to the enzyme's active site. While the enzyme is bound, the substrate cannot bind. This means that at any one time, a proportion of enzyme molecules are out of action. Rate of reaction is then reduced. Competitive inhibitors are normally very much like the substrate in structure. This is why they can bind to the active site. Non-competitive inhibitors bind to the enzyme somewhere other than the active site. ...read more.


- Make sure everything is clearly away from the experiment. - If any spillages take place wash hands with cold water straight away. - Make sure the experiment is not on the edge of the table. - Make sure none of the apparatus is on the edge. Method (Final Experiment)- - Clear the workbench and collect all the apparatus. - Set all the apparatus out on workbench appropriately. - Wear safety goggles and clear things near the workbench, example- school bag. - Get my 250cm plastic beaker for my water bath and fill it with 150cm hot water from the kettle. - I will put the thermometer in the water bath and wait for it to go to 37?C as that is the temperature I am using. - While I am waiting for that I will start getting my first concentration ready, I will get the correct amount of starch in one test tube, and the correct amount of amylase in one test tube with the dilution already done. - Then I will put three drops of iodine in my starch test tube. - When the water bath is 37?C I will put the two test tubes in. - I will wait for the solutions in the test tube to turn 37?C, when they are I will mix the two test tubes. - Immediately I will start the stopwatch, and closely observe the test tubes. - I will wait for the solution to turn colourless and immediately stop the stopwatch when it has. - Then I will wash and dry all my equipment and continue to do my next concentration. - Finally I will do the whole entire experiment two more times, so I gain reliable and accurate results. Dilution Table For Concentration Of Amylase Concentration (%) Amount Of Amylase (cm ) Amount Of Water (cm ) Amount Of Starch (cm ) Total Volume (cm ) 100 10 0 10 20 80 8 2 10 20 60 6 4 10 20 50 5 5 10 20 40 4 6 10 20 20 2 8 10 20 ...read more.

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