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Biology Coursework on Enzymes.

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Biology Coursework on Enzymes Name: Brijel Limbachia Form: 12.92 Teachers: Mr Lotsu and Mrs Stewart Enzymes in General I will first of all talk about enzymes in general. This means that I will talk about what enzymes are, how being in certain conditions affects the enzyme itself. I will also talk about how substances can increase the % transmission between the enzyme and the substrate. What are enzymes? The catalysis that takes place in organisms is defined as the acceleration of a chemical reaction by some substance which itself undergoes no permanent chemical change. These kinds of catalysts, which are in biochemical reactions, are called enzymes. Enzymes are responsible for almost all of the chemical reactions in living organisms. Without enzymes, these reactions take place at a rate that is far too slow for the pace of metabolism. An active enzyme could make a certain reaction speed up, but not all living things need all the reactions to be quick all the time. It's more accurate to say that enzymes react with simpler molecules to produce a stable reaction system in which the products of any reaction are made when they are needed, also in the amount that they are needed. All known enzymes are proteins. Enzymes are high molecular weight compounds made up of chains of amino acids that are linked together by peptide bonds. As you know that enzymes are composed of proteins, these proteins are globular proteins. These globular proteins have a complex tertiary and sometimes quaternary structure, where polypeptides are folded around each other to form a roughly spherical, or globular shape. Here is a diagram to show the three-dimensional shape of an enzyme: The green molecules are the substrate in the enzyme (on the left), and the enzyme itself is on the right. Here is a diagram to show the three-dimensional structure of an enzyme molecule: The shape of an enzyme molecule is very important, if the molecule is altered in any way, the enzyme can't combine to its substrate, therefore the enzyme will not be able to function any more. ...read more.


May cause sensitisation by inhalation and skin contact. Health effects-Eyes: dust will cause conjunctival irritation. Health effects-Skin: material will cause irritation. May cause allergic sensitisation. Health effects-Ingestion: harmful if ingested in large quantities. Health effects-Inhalation: Exposure to dust may have the following effects: - irritation of nose, throat and respiratory tract. Inhalation may cause pulmonary sensitisation and may cause bronchial spasms in asthma. Overall Trypsin is harmful/ irritant. The casein suspension really had no hazards, as it was milk powder. Now the pH buffers that I used, now these could have been acidic or alkaline, these could have been irritant as well as harmful. All I know is that NaOH and citric acid was used in order to make the pH buffers. (The pH range is from acidic pH5 to alkaline pH10). Prediction/ Hypothesis From background research I have found out that the optimum pH for the enzyme Trypsin is pH8. This therefore suggests that the enzyme Trypsin works best in alkaline conditions. Therefore from this account I can say that the enzyme Trypsin will work at its best in alkaline conditions, so this means that it will work at its best in pH's like 8,9,10 etc. This also suggests that the enzyme will not work as good in pH's below 8, meaning in acidic conditions the enzyme will not work or won't work as good. I have got scientific knowledge to prove my prediction (hypothesis). I will first talk about how pH actually affects the enzyme and substrate interaction. Here is a graph to show the effect of change in pH on enzyme activity: As you can see, that in certain pH's the enzymes will work. But this mostly depends on the type of enzyme it is. In my case, the enzyme Trypsin will work at its best in pH 8, it will also work quite good in alkaline pH's. Basically if the pH increases or decreases much beyond this optimum, the ionisation groups at the active site and on the substrate change. ...read more.


My results do help prove that my prediction was correct overall. My results relate very well with what is happening between the enzyme and pH, e.g. in and acidic environment the enzyme denatures quicker and the "odd" results take place (the solution clears, darkens, and then clears again). What I expected to get as in the results is what I got, I just didn't understand at first what the results were telling me. As the results proved my prediction correct overall. The difficulties that I experienced during the whole experiment are: Using the colorimeter- I didn't know how to use it at first, as I didn't understand what the % transmission meant. I have now learnt from this experiment what a colorimeter is and how to use it. Also what a colorimeter shows you in terms of science. The time interval- as it was every 30 seconds I had to be very quick. So human error could have taken place, hence the anomalies. Time- I had very little time, and preparing the whole experiment, meaning getting all the volume right and temperature etc. took time and therefore I had to be quick overall. I could say that because of these difficulties I got anomalies in the results. If I were to do this experiment again I would do the following changes: I would have a control as it helps explain what is taking place between enzyme and pH buffer solutions. Help me to see what I am expecting. I would also do a test on the enzyme and substrate on its own without temperature etc. affecting it. This also helps me to see what I am expecting. I would change the time interval to say every minute instead of 30 seconds this can help me avoid anomalies. I would change the method. I would have to have more time in order to not rush and so avoid anomalous results. I would not have 30 degrees Celsius at the constant temperature. This helps get accurate results. I would change the constants such as volumes of the solutions. ...read more.

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