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Liver and its role

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Liver coursework Aim: I will investigate how bile salts aid the digestion of fats by enzyme lipase, by varying the concentration of the bile salts added to the mixture containing food source and the lipase enzyme. Theoretical knowledge: The human body is adapted to many functions, including detoxification. Another important function is the metabolism, which includes the breakdown fats (triglycerides). The organ responsible for this is the liver which is found on the bottom right side of the ribcage. Fig. 1.1 is the basic structure of the liver. As we can see it is boomerang shaped and consists of many blood vessels. 'The liver is the largest internal organ in the human body, and is an organ present in vertebrates and some other animals. It plays a major role in metabolism and has a number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, and detoxification. The liver is also the largest gland in the human body. It lies below the diaphragm in the thoracic region of the abdomen. It produces bile, an alkaline compound which aids in digestion, via the emulsification of lipids. It also performs and regulates a wide variety of high-volume biochemical reactions requiring very specialized tissues.' ref. 1.1 Fig. 1.1 The interior of liver is made out of many canalicules and lobules. There is a blood vessel called hepatic portal vein. This blood vessel is very unique vessel, as it is capable of transporting three times more blood per minute than the hepatic artery (main source of oxygenated blood for the liver). Like every vein in the body, the hepatic portal vein carries deoxygenated blood. Normally veins carry blood away from organ to heart (pumps blood), while this vessel carries the blood into the liver. It brings blood rich in amino acids and glucose from the small intestine. The Liver has got more than one function in the body. ...read more.


Also lab-coat should be worn at all times as the chemicals may stain clothes. Goggles are also important as contact of bile salts or enzyme with eyes may be harmful. Any such event should be immediately reported to teacher and eye washed out with plenty of cold-water. Prediction Based on the scientific research and the preliminary work I can draw following predictions: * The higher the concentration of the bile salts the higher the pH's change: This is because, higher concentration of bile salts will emulsify more lipid molecules, so more substrates will be available to form enzyme-substrate complex with the lipase enzyme. This means that there will be higher concentration of substrates available to bind to the active site of the enzyme and to be broken down. The more lipid molecules broken down the more fatty acid triplets produced, so the pH will be changing more noticeably. However there will be a point at which the pH will be decreasing over small rate. This is because at this point the pH of the solution will drop to the level, at which the pH of the enzyme's natural environment will be so different that the enzyme will not work at its highest rate- it will start becoming denaturated. At this point there will be less hydrolysis reactions, less fatty acid triplets produced, and hence the pH will be dropping at slower rate. Variables: Dependent variable is the variables that will automatically change when the independent variable is changed. In this experiment the pH change will be the dependent variable. This is because as I have mentioned before the pH change is directly related to the concentration of the bile salts. The pH change will be different when I am going to use different concentrations of the bile salts (the higher the concentration of bile salts the bigger the pH change). This variable will be controlled by a pH probe, connected to palm top. ...read more.


Also such probe doesn't need to be calibrated each repeat, which could be the source of error. This piece of apparatus would increase the reliability of my experiment. * Swap measuring cylinders for glass pipettes. This is because there was some solution inside the measuring cylinder after I poured it into boiling tubes- this liquid has been trapped inside the cylinder. The glass pipette is more accurate piece of apparatus as it measures the volume more precisely. Its bigger scale allows better judging what is the exact amount of liquid poured into the tube. Also the glass pipette consists of sucking system which allows eradicating the problem of trapping of the substance, as it can be blown out of it. This is important, as the amount of the substance will be the same each repeat (as even drop of lipase enzyme consist of many enzymes to carry out hydrolysis reaction). This will also improve accuracy and reliability of the experiment * Mixing of the substances would be another introduction to improved method. This is because I have noted that there was separation between layers of different substances. Stirring it would be a good idea, as there could be some substrates in the bottom layer, while free enzymes could be on the top layer. * Take repeats every 1 minute. This would increase the reliability of my experiment, as there would be more points on the graph, so maybe the line of best fit wouldn't have to be drawn. * Use more concentrations of the bile salts. I would like to change concentrations in 10% intervals. This would allow me to compare accurately the best bile salt concentration for the action of lipase enzyme to hydrolyse lipids. This would increase the strength of the conclusion drawn, and determine best concentration for emulsification. Above information's are suggestions of improving the experiment. However the results obtained in this experiment are reliable themselves, as they are matching my prediction based on the scientific research. Also they allow drawing conclusions which are supported by both science and predictions. ...read more.

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