Chapter 5-Molecules of lifeFour ClassesCarbohydratesLipidsProteinsNucleic AcidsMacromolecules: Large molecules composed of thousands of covalently connected molecules.-Concept 5.1: Macromolecules are polymers built from monomersPolymer: Big molecules built through monomers3 of 4 Classes are polymersCarbohydratesProteinsNucleic Acid-Synthesis and Breakdown of polymersEnzymes: Macromolecules that speed up the chemical reaction.Dehydration reaction: two monomers bond through the loss of water.Hydrolysis: Reverse of dehydration.-Diversity of PolymersEach cell has thousands of different macromolecules.Macromolecules differ between species and with in a species.An immense variety of polymers can be built from a small set of monomers.-Concept 5.2: Carbohydrates a.k.a FuelCarbohydrates are monosaccharaides of single sugars.They are polysaccharides built from monosaccharaides.-SugarsMonosaccharaides have molecular formulas that are multiples of CH2OGlucose (C6H12O6) is the most common monosaccharaideClassified by:1) Location of carbonyl Group as a Keytone or Aldehyde 2) Number of CarbonsThough often drawn as linear chains, in aqueous solutions form rings.The oxygen on carbon 5 binds to carbon 1 and forms ring of carbon attached to oxygen. (Carbon 6 is outside the ring)Atoms on the right side of the chain are found on the inferiorside (Bottom)Disaccharide: Two monosaccharaides after dehydration reaction.Glycoside Linkage/Covalent BondMaltose= (Glucose + Glucose) from digestion of starch.Lactose= (Glucose + Galacatose) Sugar in milk.Sucrose = (Glucose + Fructose) Table Sugar.Polysaccharide: Polymers of sugars, have store and structural roles.Two things determine structure and function.Sugar MonomersPositions of glycosidic linkages-Storage PolysaccharideStarch: Storage polysaccharide of plants, consisting of only glucose monomers.Plants store excess starch as granules within chloroplasts and other plastids.Simplest form of starch is amylose.Glycogen: Storage of polysaccharides in animals.Humans and other vertebrates store glycogen mainly in the liver and muscle cells.-Structural PolysaccharidesPolysaccharide cellulose is a major component of the tough wall of plants.Like starch, cellulose is a polymer of glucose, but the glycosidic linages differ.The differences based on two ring forms for glucose: Alpha and BetaAlpha: OH of carbon 1 points down.Beta: OH of carbon 1 points up.Polymers with alpha glucose are helicalPolymers with beta glucose are straightH atoms can bond with oh groups of other chains.Parallel cellulose molecules held together this way are grouped intro microfibrils, which form strong building materials for plants.In straight structures, H atoms on one strand can bond with OH groups on other strandsEnzymes that digest starch by hydrolyzing alpha linkages, cant hydrolyze beta linkages in cellulose.Cellulose in human food passes through the digestive tract as an insoluble fiber that cannot be digested.Some microbes use enzymes to digest, cellulose.Many herbivores, from cows to termites have symbiotic relationships with these microbes.Chitin, another structural polysaccharide, is found in the exoskeleton of arthropodsChitin also provides structural support for the cell walls of many fungi; Ex: mushrooms-Concept 5.3 LipidsDo not form polymersHydrophobicBecause they are hydrocarbons (Non-Polar)Most biologically important fats are phospholipids and steroids.-FatsTwo typesFatty AcidsFatty acids consist of a carboxyl group attached to a long carbon skeleton.Simplest of lipids Biological fatty acids contain from 12-24 carbons.Glycerol3 Carbon alcohol with hydroxyl group attached to each carbon.Fats separate from water molecules because water forms hydrogen bonds with each other and excludes the fats.Fatty Acids are joined to a glycerol by an ester linkage creating triacylgcerol or triglyceride.Dehydration reaction connects them.Important energy stores.Vary in length, solids at room temperature, stable, and stack.Saturated fatty Acid: Maximum amount of hydrogen atoms possible and nodouble bonds.Unsaturated fatty acid: one or more double bonds, liquids at room temperature, like oil. Diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits.Hydrogenation is the process of concerting unsaturated fats to saturated fats.Trans Fats contribute to cardiovascular disease more than saturated fats, hydrogening vegetable oils also creates unsaturated fats with trans double bonds.Trans configuration.Certain unsaturated fats are not synthesized in human body.Not naturally produced, must be supplied in the diet.Essential fatty acids include the omega-3 fatty acids, required for normal growth, protect against cardio-vascular disease.Major function of fats is energy storage.1g of fat stores more than twice as much energy as a gram of a polysaccharide, such as starch.Humans and animals store fat in adipose cells.Adipose tissue also cushions vital organs and insulates the body.-Phospholipids2 fatty acids and a phosphate group are attached to a glycerol.Hydrophilic head because the phosphate group is hydrophilic and polar.When added to water, they self assemble into a bilayer with phobic tails point toward the interior.Results in a bilayer arrangement found in cell membranes.Major component of all a cell membranesCell can use exocytosis to move things our of the cell through its membrane.-SteroidsLipids characterized by a carbon skeleton consisting of four fused ringsDiffer by the chemical groups that are attached to the rings.Cholesterol: an important steroid is a component in animal cell membranes.Cholesterol is the precursor from which other steroids are synthesized.Although it is essential, high levels in the blood stream lead to cardio vascular disease.Steroids function as hormones.Vitamin D is a steroidSynthesized in the skin due to the sun’s rays.Vitamin D is important for calcium absorption in the digestive system and bone formation.Concept 5.4: ProteinsProteins account for more than 50% of the dry mass of most cells.Protein functions include structural support, storage, transport, cellular communications, movement, and defense.Structural support: Hair,
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