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ch 5- the structure and function of macromolecules

ch 5- the structure and function of macromolecules -...

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Chapter 5: The Structure and Function of Macromolecules Polymers Long chains of a single subunit (the monomer) attached repeatedly usually by a covalent bond Formation of polymers: occurs through a condensation aka dehydration reaction (removal of H 2 0) this requires energy Breakdown of polymers: occurs through a hydrolysis reaction (addition of H 2 0) this releases energy Although biological polymers are constructed from only 40-50 monomers, there is HUGE diversity in the products because the arrangement of the polymers can differ greatly Carbohydrates = sugars Monosaccharide: (CH 2 O) n this is the monomer of di/polysaccharides Sugars can be classified as: o aldoses/ketoses: depending on the location of the carbonyl groups o trioses/pentoses/hexoses: depending on the number of carbon atoms Glycosidic bonds link monomers together it is a covalent bond between 2 monosaccharides Polysaccharides: o Store Energy Starch: energy storage in plants; polymer of -glucose; 1-4 linkages Glycogen: energy storage in animals o Provide structural support Cellulose: major component of plant cell walls; polymer of β-glucose; 1-4 linkages Chitin: structural polysaccharide in exoskeletons of arthropods o vs. β conformation: = hydroxyl group on carbon 1 points down β = hydroxyl group on carbon 1 points up Humans cannot digest starch because we do not have enzymes to hydrolyze β linkages! Lipids Fats/triacylglycerols : Glycerol + 3 fatty acids o Fatty acids: carboxyl group attached to long hydrocarbon chain (16-18 carbons) Saturated: no double bonds; these types of fats are able to pack together tightly
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Unsaturated: fatty acid chain contains at least one double bond, which creates kinks in the chain, and thus these fats cannot pack as tightly o Energy storage Phospholipids o Hydrophilic head group + 2 hydrophobic fatty acid tails o Amphipathic the head is polar and the tails are non-polar; this causes self-assembly into bilayers o Make up the lipid bilayers in cells (heads make up the outside of the bilayer because they are polar, tails make up the inside because they are non- polar) Steroids : 4 fused carbon rings o Cholesterol/sex hormones Proteins: Monomer: amino acid Amino acids are linked by peptide bonds into polypeptides; proteins consist of 1 or more polypeptides Amino Acids (see figure 5.17 on pg. 79) o
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