lab report 1

lab report 1 - Biological Materials and Enzyme Action...

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Introduction: Our laboratory experiments were divided into two parts, the first of which aimed at identifying various classes of food (Part A), and the second of which aimed at understanding the digestion of foods (Part B). The compounds that we attempted to classify in Part A were carbohydrates, lipids, and proteins. Along with nucleic acids, these constitute the four basic compounds of biological material. Rather than testing a specific hypothesis, we used various chemical techniques to merely identify the class to which various food samples belonged. These tests were conducted based on the fact that biological compounds produce color reactions when interacting with specific chemical reagents. Starch (carbohydrate) reacts with iodine solution (IKI) to produce a dark purple color. Simple sugars (carbohydrates) react with Benedict's solution to produce a green or bright red- orange color. Finally, Sudan IV dissolves in lipids and produces a red-orange color. By mixing various food samples with these chemicals, we were able to identify whether each sample contained starch, simple sugars, or lipids. For Part B of our laboratory work, we tested the effects of pancreatic enzymes on the chemical breakdown, or hydrolysis, of the basic compounds. Furthermore, we subjected the enzymes to different conditions so as to observe the effects of temperature and pH on enzyme efficiency. This included exposing the enzymes to a combination of boiling, freezing, acidic, and basic conditions before allowing them to act on the compound samples. We conducted our experiments based on the following hypothesis: Pancreatic enzymes work most efficiently at catalyzing the chemical reactions in biological systems when at 97DC (normal human body temperature). The further the temperature deviates in either direction, the less efficient the enzymes should be. Furthermore, an environment with a pH of 7 should be optimum for enzymes to function, with both acidic and basic conditions minimizing their effects. To test this hypothesis and the aforementioned classifying of food samples, we employed the following methods. Materials and Methods: For Part A, we began by testing for starch in four samples of food. In each of four test tubes we placed a small amount of potato scrapings, apple scrapings in water, egg white, and cracker crumbs in water. We added a few drops of iodine solution (IKI) to each test tube and observed and visible color change. To test for simple sugars, we placed samples of chopped liver, potato scrapings, apple scrapings, and whole
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This note was uploaded on 05/03/2008 for the course BISC 220LG taught by Professor Mcclure during the Spring '07 term at USC.

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lab report 1 - Biological Materials and Enzyme Action...

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