Lab 4 answers - LAB EXERCISE#4 answers What if we start...

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1 LAB EXERCISE #4 answers : What if we start with carbon, hydrogen, and oxygen? Pre-lab Assignment: Use the Background document for information. Write an Experimental Protocol for Reducing Sugars (Benedict’s test) and Starch (I 2 KI). This means that you will write 2 individual experimental protocols. (There is no protocol for Lipids.) Follow the directions for writing an Experimental Protocol in the T hinking and Writing Scientifically document. Use the Background information found in the Lab Exercise #4 folder in Course Documents. Pre-lab Experimental Protocols : Maximum points if you follow the guidelines below. Correctly stated Purpose ; being no more than 1–2 sentences in length. Correctly stated Hypothesis ; being no more than 1 sentence in length. Correctly stated Null Hypothesis ; being no more than 1 sentence. Correctly stated Predictions ; multiple predictions, a separate one for each of the solutions to be tested with each reagent; written as “If…then…” statements. [For Reducing Sugars , you will need to look at the figures of the organic structures of the monosaccharides, disaccharides, and polysaccharides to help you visualize the reactions occurring in the Background information (a separate document in the folder). (Look for at least one anomeric carbon that has a free OH group attached to it. If it has this hydroxyl group on the anomeric carbon, then the sugar can react with the copper ions in the Benedict’s reagent.) Correctly stated Rationales: If you have 5 predictions for a particular test, you will have 5 rationales; one for each prediction; written as: “If…then…because...” statements. Objectives: To understand the biochemical composition of macromolecules through qualitative observations. Since results are based upon qualitative observations (color changes of solutions) rather than quantitative observations (measurement of how much the color changes) it is not necessary to be extremely precise with your measurements. Compare Expected results (Experimental Protocol) and Observed results (Lab Experiment). You will have Expected results before performing your experiment. You will then compare your Expected results to your Observed results at the end of class. Remember, all scientists do a literature research (usually doing journal searches, but in your case, probably reading the Background information in the lab exercise ) before starting any experiment. By the end of the lab, you should be able to summarize the following: Polymer tested Subunits of polymer (monomers) Name of chemical test (what reagent was used) Evidence of a negative control (variable being tested is not present) Evidence of a positive test (beginning and end colors of tested item) How the test works (what interactions are occurring between the reagent and macromolecule) Where is the polymer found in the cell P ositive and Negative Control In each of the experiments today you will have two controls, a positive and negative control. A positive control contains the variable for which you are testing. It identifies what you expect to
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