113lecture0306 - BIOLOGY 113 - MICROBIOLOGY Lecture 3:...

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BIOLOGY 113 - MICROBIOLOGY Lecture 3: Macromolecules - Carbohydrates, lipids, proteins, nucleic acids Much of the organic matter of cells is found in the form of macromolecules, which are usually polymers formed by covalent bonding of many repeating monomers - When two monomers are joined together, the reaction usually involves the elimination of a hydrogen atom from one monomer and a hydroxy group from the other; this is called dehydration synthesis (Tortora et al., Figure 2.9) and results in formation of a molecule of water. - In the reverse reaction, hydrolysis, atoms from a molecule of water are incorporated as the covalent bond joining the monomers is broken The carbohydrates (general formula (CH 2 O) n ) are a diverse group of organic compounds that includes the sugars and starches. - Carbohydrates perform a number of functions in living cells, but are especially important as components of structural elements (e.g., cell walls) and as energy storage compounds. - The simplest carbohydrates are the monosaccharides or "simple sugars", such as glucose, fructose and ribose; simple sugars are classified according to the number and arrangement of carbon atoms. - Disaccharides are formed when two monosaccharides bond in a dehydration synthesis reaction = For example, sucrose is formed from a molecule of glucose and a molecule of fructose (Tortora et al., Figure 2.9) = Note that the molecular formulae for glucose and fructose are identical - C 6 H 12 O 6 - but that their properties differ due to the different arrangement of the atoms = Similarly, dehydration synthesis of the monosaccharides glucose and galactose forms the disaccharide lactose - Polysaccharides are formed from dehydration synthesis of numerous monosaccharides into long polymers = The monosaccharides may be identical (as in starch and cellulose, which are polymers of glucose) or diverse (as in some of the polysaccharides found in bacterial cell walls) = Some polysaccharides, include starch and glycogen (another glucose polymer), have side chains branching off the main structure. The
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This note was uploaded on 11/24/2011 for the course BIO 113 taught by Professor Staff during the Fall '09 term at Rutgers.

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113lecture0306 - BIOLOGY 113 - MICROBIOLOGY Lecture 3:...

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