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Protein Purification Lab

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G4 lab report Topic Protein digestion rate in human stomach. Choosing the topic Most members in our G4 group want to become doctor so our topic focuses mainly on medicine and healthcare. I spent my summer vacation in China this year. My grandfather suffered from diabetes and his doctor told him not to eat too much because that would increase his blood sugar. He had poor diet for years which caused him anemia (condition in which the body does not have enough healthy red blood cells or hemoglobin). This disease can be caused by poor diet and anorexia nervosa which is an illness of eating disorder characterized by low body weight and body image distortion with an obsessive fear of gaining weight. I suggested him to take protein powder I brought form U.S. As a bodybuilder, I knew that protein can make people healthier by putting on more muscle. But it's not all what a responsible physician needs to know! Instead, a doctor should be able to suggest patient to use different types of proteins at different time because of the different digestion rate of protein. Another reason is a good diet cannot be replaced by protein powder. That's the reason we chose our G4 topic and we would like to apply our result to healthcare fields in the future. Research question Is the protein digestion rate of different solid proteins different in human stomach and what factors can contribute to the difference between them? Based on the theory behind the prediction, what type of solid protein will have the fastest and the lowest protein digestion rate? ...read more.


Materials used 5 x 500 ml beaker 1 x 100 ml graduated cylinder 5 x Pepsin capsules (Solaray Dietary Supplement from Vitamin Shoppe) 1 x Scale (uncertainty: +/- 0.005g) 1 x Thermometer 2 x Bottle of 1M HCl solution (20.0 ml of 6.00M HCl with 100 ml tap water) 3 x Safety goggles 3 x Pairs of safety gloves 1 x Cooking pot (as big as possible) 1 x Chopstick Procedure: 1) Measure 10.0 g of each of 5 solid proteins (tofu, chicken, egg white, cheese and nuts) 2) Put 180 ml of tap water into each of 500 ml beakers. 3) Put 20.0 ml of 1.00M HCl into each beaker (5 in total). 4) Labe the beakers with number 1 to 5. 5) Put 1 pepsin capsule into each beaker (only the powder inside the capsule) 6) Put the chicken breast into beaker #1, tofu into beaker #2, cheese into beaker #3, nuts into beaker #4 and egg white into beaker #5. 7) Put 4 liters into the cooking pot and start heating it until it reaches 37.0 oC. 8) Put all 5 beakers into the cooking pot and using thermometer check the temperature of the beakers every 15 minutes till the end of the experiment (7 times). 9) Measure the weight of the solid proteins in each beaker every 30 minutes for 4 times in total. Use chopsticks to transfer the food. Data collection: see handout attached Data processing: The chart below shows the measurement of the temperature in Celsius degrees of the beaker #1 as sample every 15 minutes. ...read more.


but soon I realized that same size samples would have different weight (eg. same size cheese is heavier than egg white). But it is a controversial issue because the amount of surface area touching the enzyme is an important factor which decides the protein digestion rate. 10.0 g of cheese is much smaller than 10.0g of egg white thus have much smaller surface area and enzyme will work better with egg white than with cheese because egg white and pepsin will have more contact area. I failed to take this factor into consideration and it caused another systematic error in the result. Although the data supported our hypothesis, we cannot say that the data is valid due to the errors we made during the experiment. Improving the investigation Many errors in our investigation were due to lack of equipment. The realistic suggestion of correction the error is to use hot plate to stir the solution instead of using chopstick. The hot plate does not touch the solution direction thus would not carry any chemical with it. The hot plate can also warm up the solution which can be more accurate than using stove. The temperature can also be more easily controlled by using the hot plate because it is easy to overheat the solution using the stove. Regarding the surface vs. weight issue, it would be better to use the samples of the same surface area and record the weight of each one. Although the samples would have different weights, researcher can use formula to calculate the protein digestion rate for each sample without leaving any factor into consideration. Resources Background information: http://en.wikipedia.org/wiki/Stomach http://www.mamashealth.com/organs/stomach.asp http://answers.yahoo.com/question/index?qid=2008201133859AAjAb9r http://www.iscid.org/encyclopedia/Hydrophilic http://www.iscid.org/encyclopedia/Hydrophobic http://www.bodybuilding.com/fun/nutrient.php?id=1124 http://wiki.answers.com/Q/How_does_ph_affects_the_rate_of_chemical_reaction Biology, 7th Edition by Campbell Reece. Publisher: Benjamin Cummings, 2005 Picture: http://www.trialsightmedia.com/exhibit_store/images/stomach.jpg http://www.holistic-wellness-basics.com/images/how-enzymes-work.jpg ...read more.

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