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Bio lab 3 report.pdf - Goals Your active participation in...

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Lab 3: MacromoleculesGoalsYour active participation in these laboratory exercises will:Help you to understand the structures and functions of nucleicacids, carbohydrates, lipids, and proteinsIntroduce you to chemical tests used to determine the presence ofcarbohydrates, lipids, and proteins in samplesIntroductionImagine a factory in which automobiles are produced. You might envisionpeople busily assembling cars from gears, nuts, bolts, and the like. In muchthe same way, our bodies’ cells produce macromolecules from small,carbon-based molecules. There are four different groups ofmacromolecules: carbohydrates, lipids, proteins and nucleic acids. Just aseach of their structures are different, so too are each of their functions.Macromolecules serve a myriad of functions including energy storage,transport, and transmission of information. The purpose of this lab is tointroduce you to macromolecules by learning about their structures andfunctions, and performing chemical tests that detect their presence.Most of the following lab exercises are qualitative assays which will enableyou to determine whether or not a particular macromolecule is present ina sample. These assays are not intended to yield information regardingthe quantity of the macromolecule being tested. To ensure the validity ofthe results, both positive (substance present) and negative controls(substance absent) are included. The assays are based on chemicalreactions that produce observable color changes.Part A:CarbohydratesCarbohydrates are composed of simple sugars called monosaccharides.Monosaccharides contain the elements carbon, hydrogen, and oxygen ina typical ratio of 1:2:1. Simple sugars usually have anywhere from three toseven carbon atoms which form either a ring or straight chain structure.The functional groups (parts of a molecule that get involved in a chemicalreaction) of a monosaccharide are the hydroxyl group, -OH and thecarbonyl group, C=O. When the sugar is in a straight chain form, the1
placement of its carbonyl group defines it as either an aldehyde(carbonyl group located at the end of the chain) or a ketone (carbonylgroup located inside the chain). An aldehyde is a reducing sugar,meaning that it can lose an electron and become oxidized to form eithera carboxylic acid or a carboxylate ion, depending on the pH of thesolution. Two monosaccharide molecules can combine to form adisaccharide. Familiar disaccharides include sucrose (table sugar) andlactose (milk sugar). Many simple sugars linked together form apolysaccharide.Perhaps the most noted function of carbohydrates is provision of energy.Monosaccharides can easily cross the plasma membrane of cells andthus be immediately metabolized to make ATP energy.In contrast,disaccharides and polysaccharides must be digested first before beingutilized by cells. For this reason both plants and animals formpolysaccharides to store energy. Besides providing energy,polysaccharides also form structural components; cellulose is found in thecell walls of plants and chitin is found in invertebrate exoskeletons.

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Term
Fall
Professor
NoProfessor
Tags
DNA, Glucose, Benedict, Per Table Group

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