The Structure and Function of Large Biological MoleculesBiological MacromoleculesOrganellesThe Nuclear Envelope (Nuclear Membrane)The NucleusRibosomesThe Endoplasmic Reticulum (E.R.)Smooth Endoplasmic ReticulumRough Endoplasmic ReticulumSecretory ProteinsGolgi ApparatusLysosomesEnergyDNAMitochondriaChloroplastsPeroxisomesCytoskeletonS.J. Singer and G. NicolsonMembrane FluidityMembrane ProteinsIntegral ProteinsAquaporinsGated ChannelsSelective PermeabilityDiffusionOsmosisLarge MoleculesDepression MedicationsIon PumpsChapter 5 NotesThe Structure and Function of Large Biological Molecules- Polymers are large molecules consisting of many identical or similar subunitsconnected together.- Monomer is a subunit (or building block) of a polymer- Polymerization: the bonding of many small subunits (monomers) to form long molecules (polymers).o One of the subunits is a monomer. o Two of the subunits make up a dimer. o 3+ of the subunits make up a polymer.- Condensation reactions—are polymerization reactions in which the covalent linkage of the monomers is accompanied by the “removal of a water molecule.o Functional groups are removed and water is formed.o Large complex molecules are made by condensation reactions.- Hydrolysis—the breaking of the covalent bond between two monomers by the addition of water.o Adding water breaks down large molecules. Hydrolysis adds a water molecule, breaking a polymer bondo The opposite of condensation reactionsBiological Macromolecules- The four classes of polymers (the most important classification of molecules in living systems):o Carbohydrateso Lipidso Nucleic acidso ProteinsCarbohydrates- Carbohydrates are used as fuels and building material- Carbohydrates are organic molecules made of sugars and their polymerso Monosaccharides—one simple sugar o Disaccharides—two simple sugars togethero Polysaccharides—3+ simple sugars together- Without carbohydrates, one will die- Carbohydrates are not linked to weight gain, calories are. It doesn’t matter what you eat, it matters how much you eat.- Carbohydrates are classified by the number of simple sugars - Monomers are simple sugars called monosaccharides. In order for a sugar to be classified as a monosaccharide, there must be a ratio of 1 carbon to 2 hydrogen to 1 oxygen- Carbohydrates contain only carbon, hydrogen, and oxygen, which occur in the ration of 1-2-1 for C, H, and O- Monosaccharides can be joined to form disaccharides and polysaccharides.- Glycosidic linkage is a covalent bond formed by a dehydration synthesis between two sugar monomers.Polysaccharides- Polysaccharides are macromolecules that are polymers of a few hundred or thousand monosaccharides.- Formed by enzyme-mediated condensation reactions- Biological functionso Energy storage (starch and glycogen)o Structural support (cellulose and chitin) Cellulose is in plants as cell walls Chitin is in anything with an exoskeleton or shell; a lot of fungi and mushrooms use chitin too Storage Polysaccharide- Stored sugars can be hydrolyzed as needed- Starch is a glucose polymer that is used as a storage polysaccharide in animals.- Glycogen is a glucose polymer that is used as a storage polysaccharide in animals.o Stored in the muscle and liver of vertebrateso Glycogen is like fuel—Michael Phelps carb loads for competitions in order to increase glycogen levels and sustain his speed in racesGlycogen- If there is more glucose in your bloodstream than your body needs, the excess glucose is linked together and stored as glycogen in your muscles and liver.- When energy is needed, glycogen is quickly broken down to release glucose into the bloodstream for short-term energy needs.- Once glucose stores are full, excess glucose gets converted to fat for long-term energy needs.- The brain can only survive off of glucose; it can’t burn fat or protein. You can’t retain information as easily when hungry because your brain is runninglow on glucose.Carb-loading- A 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 fatigue.- 2 phase process:o Depletion Phase—about a week before competition. Extremely low-carb diet and rigorous exercise.o Loading 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 glycogen. Water weight- The first stage of any diet; usually involves rapid and dramatic weight loss.- This is because glycogen is being deleted in the muscles and liver as caloric intake is reduced.- Every ounce of glycogen in the body can have as much as four ounces of water bound to it.Structural Polysaccharides- Structural polysaccharides include cellulose and chitin- Cellulose is a linear unbranched polymer of glucoseo Cellulose (fiber) cannot be digested by the human body. It never gets stored in fat because it cannot be digested; it doesn’t count towards calories.o Cellulose cannot be digested by most animals because they lack the enzyme that can hydrolyze the linkage in celluloseo Most abundant organic molecule on the planeto Cellulose reinforces plant cell wallso Hydrogen bonds hold the cellulose strands togethero The longer a digestive system in an animal is, the more plants/cellulose they ingest. Animals that can digest cellulose have an enzyme in their stomach that humans lack.- Chitin is a structural polysaccharide that is a polymer of an amino sugar.o Forms the exoskeleton of arthropods (insects, crawfish, etc.)o Found in the cell walls of some fungiLipids- Lipids are mostly hydrophobic (nonpolar) molecules with diverse functions- Lipids are a diverse group of organic molecules that are insoluble in water, but will dissolve in nonpolar solvents (e.g. ether, chloroform, benzene)- Important lipid types are: fats, phospholipids, and steroids.Functions of Fats and Oils- Energy storageo One gram of fat stores twice as much energy in its chemical bonds as one gram of polysaccharideo Because of the higher energy per gram, energy storage is more compact with fats and oils than with carbohydrates. Fats and oils are denser than carbohydrates.- Why do we crave fats?o Fats store enormous amounts of energyo Because of this, humans have actually evolved an extremely strong taste preference for foods that are high in fats During times when food was scarce, those who had a preference for foods that were high in fat survived. This is how the gene
View Full Document
Unlocking...