chapter 5

chapter 5 - Chapter 5 1 Describe the processes by which...

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Chapter 5 1. Describe the processes by which most covalent linkages are formed and broken in organic polymers. Dehydration Synthesis is the reaction in which two molecules are covalently bonded. When this bond forms, each of the two monomers donates part of the molecule that was initially lost; one hydroxyl is provided and one hydrogen. This donation of molecules is repeated in order to form a polymer. Hydrolysis is the process in which molecules are broken down. The bonds are disassembled by the addition of water molecules; a hydrogen from the water attaching to one monomer and a hydroxyl joining onto the neighboring monomer. 2. What are the characteristics of all carbohydrate monomers? Glucose is the most important element in the formation of a monosaccharide. Monosaccharides, in general, are central nutrients for cell usage by extracting the stores energy in a glucose molecule. In addition, the skeleton of monosaccharides are used as for basic material in the synthesis of other kinds of organic molecules. 3. Thoroughly compare and contrast starch, glycogen, cellulose, and chitin. Starch is a storage of energy in plant cells. It is bonded by a 1-4 linkage and these bonds create a helical structure. Amylose is the simples form of starch and is unbranched. Amylopectin, another subunit of starch, is more complex form, which has a branched polymer in a 1-6 branch. Starch is formed with Alpha linkages: the monomers are all facing downward. Starch is synthesized by the plant, which in turn saves the excess for future use. Glycogen is a storage of glucose within animals. In addition, glycogen is also stored within the liver and muscles of humans and other vertebrates. When sugar is needed, hydrolysis of glycogen occurs and in turn releases the necessary glucose. Cellulose is necessary in the walls of plant cells. Glucose monomers of cellulose are all in the Beta configuration: every other glucose monomer is facing the opposite direction relative to the other. In addition, a cellulose molecule is straight and does not contain branches. Though most fruits, vegetables, and grain contain a large amount of cellulose, the body does not have the enzymes to break it up. Chitin is important in the exoskeleton structure of insects, crustaceans, spiders, and related animals. Chitin is also common in fungi, where it is used as the building material for the cell walls. The structure of chitin is similar to cellulose, though chitin contains a nitrogen-containing appendage on the glucose monomer.
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4. What are the chemical building blocks and biological importance of fats, phospholipids, and steroids? Fats
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This note was uploaded on 09/27/2011 for the course BIOL 101 taught by Professor Fevzidaldal during the Fall '08 term at UPenn.

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chapter 5 - Chapter 5 1 Describe the processes by which...

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