PolymersLarge molecules consisting of many identical or similar subunits connected togetherMonomer is a subunit (building block) of a polymerPolymerization: bonding of many subunits (monomers) to form long molecules (polymers)Monomer Dimer (2 monomers) PolymerCondensation reactions: polymerization reactions in which the covalent linkage of the monomers is accompanied by the “removal” of a water moleculeHydrolysis: breaking of the covalent bond between two monomers by the addition of waterFour important classes of polymers:CarbohydratesUsed as fuels and building materialOrganic molecules made of sugars and their polymersMonosaccharides Disaccharides PolysaccharidesClassified by the number of simple sugarsMonomers are simple sugars called monosaccharidesContain only carbon, hydrogen, and oxygen, which occur in the ratio of 1-2-1 for C, H and OGlycosidic linkage is a covalent bond formed by a dehydration synthesis between two sugar monomersPolysaccharides are macromolecules that are polymers of a few hundred or thousand monosaccharidesFormed by enzyme-mediated condensation reactionsBiological functions: energy storage (starch and glycogen), structural support (cellulose and chitin)Stored sugars can be hydrolyzed as neededGlycogen: glucose polymer that is used as a storage polysaccharide in animals (stored in the muscle and liver of vertebrates)Starch: is a glucose polymer that is used as a storage polysaccharide in plantsGlycogenMore glucose in your bloodstream than your body needs, the excess glucose is linked together and stored as glycogen in your muscles and liverWhen energy is needed, glycogen is quickly broken down to release glucose into the bloodstream for short-term energy needsOnce glycogen stores are full, excess glucose gets converted to fat for long-term energy needsCarb-loading: process by which athletes are able to double or triple the amount of glycogen stored in their muscles. Used to delay the onset of muscle fatigueDepletion Phase: about a week before competition… extremely low-carb diet and rigorous exerciseLoading Phase: 2 days before competition… super high-carb diet and no exercise. Achieves a blood glucose level that is higher than necessary, so excess glucose gets converted to glycogenWater Weight: the first stages of any diet usually involve rapid and dramatic weight lossBecause glycogen is being depleted in the muscles and liver as caloric intake is reducedEvery ounce of glycogen in the body can have as much as four ounces of water bounded to itStructural Polysaccharides (cellulose and chitin)Cellulose: linear un-branched polymer of glucoseMost abundant organic molecules on the planetCellulose reinforces plant cell wallsHydrogen bonds hold the cellulose strands togetherCannot be digested by most animals because they lack the enzyme that can hydrolyze the linkage in celluloseChitin: structural polysaccharide that is a polymer of an amino sugarForms the exoskeleton of arthropods (insects, crawfish, etc.)Found in the cell walls of some fungiLipidsMostly hydrophobic molecules with diverse functionsDiverse group of organic molecules that are insoluble in water, but will dissolve in non-polar solvents (e.g. ether, chloroform, benzene)Important lipid types are: fats, phospholipids, and steroidsFunctions of fats and oilsEnergy storage: one gram of fat stores twice as much energy in its chemical bonds as one gram of polysaccharidesBecause of the higher energy per gram, energy storage is more compact with fats and oils than with carbohydratesBecause fats store enormous amounts of energy, humans have actually evolved an extremely strong taste preference for foods that are high in fatsOlestra: “fake fat” designed to be similar to fats in taste and texture, but it cannot be digested by humansInstead of being a triglyceride with 3 fatty acids linked to a glycerol, it has 8 fatty acids attached to a molecule of sucroseStill binds to same taste buds, but it doesn't get digested because the molecule is so complexFats: humans store fat in adipose tissue cells, which swell and shrink as fat is added to or taken from themInsulates the body and protects vital organsSaturated and UnsaturatedSaturated: all carbons in chain are fully saturated with hydrogen (mostly solid, butter. Makes cookies softer)Unsaturated: double bonds result in fewer hydrogen atoms on carbon chain (an oil, healthier: less likely to leave residue on the walls and less likely to cause heart disease)Phospholipids: have 2 ends that behave completely different in waterHydrophilic heads and hydrophobic tailsWhen phospholipids are added to water, they self-assemble into a bi-layer that shield their hydrophobic portion from waterRegulate the passage of water in and out of the cellSteroids: class of lipids that includes many hormonesCharacterized by a carbon skeleton consisting of 4 fused rings with various functional groups attachedIncludes cholesterol, a component of animal cell membranes. Used as a molecular precursor for many steroidsProteins: poly-amino acids held together by peptide bondsReferred to as molecular toolsCalled peptides or polypeptidesTwo standard functional groups: amino and carboxylVariable side-chain “R” which has other functional groupsThe monomers are amino acidsAmino acids are divided into 3 classes determined by the properties of their side-chains (20 amino acids)Nonpolar (9), Fig. 5.17:Polar (6), Fig. 5.17: Serine, Threonine, Cysteine, Tyrosine, Asparagine, GlutamineCharged or Ionic (5), Fig. 5.17:Acidic: Aspartic acid, Glutamic acidBasic: Lysine, Arginine, HistidinePrimary Structure: the specific sequence of amino acids in a particular proteinChanges in primary structure can result in changes in all the remaining levels of structureSecondary Structure: most proteins have repeated polypeptide segments that are coiled or folded into patternsThese are the result of hydrogen bonding between the components of the amino acid backbone (not the side-chains)Tertiary Structure: the overall 3-D shape of a polypeptide that results from interactions between the side-chains of the various amino acidsCan also involve hydrophobic interactions at the core of the polypeptideHydrophobic effect is responsible for protein foldingHydrophobic residues (core) tend to cluster together on the inside of a folded protein, away from water.Quaternary Structure (not all have this): some proteins consist of two or more polypeptide subunitsThe aggregation pattern of these subunits is
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