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UW-Milwaukee BIOSCI 150 - Macromolecules

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Outline of Last LectureOutline of Current LectureCurrent LectureMacromoleculesCarbohydratesStructuresStarchLipidsFatsPhospholipidsSteroidsProteinsAmino Acid:Protein StructureDenaturationProtein FunctionNucleic AcidsBIO SCI 150 1st Edition Lecture 4Outline of Last Lecture I. Carbona. Propertiesb. Hydrocarbonsi. Isomersii. Functional GroupsOutline of Current Lecture - Macromoleculeso Propertieso Carbohydrates Structures Starcho Lipids Fats Phospholipids Steroidso Proteins Amino Acids Structure Denaturation Functiono Nucleic AcidsCurrent LectureMacromoleculesLife requires many large and complex structures. These are made by combiningsmall subunits…- Monomer -+ Polymer- Synthesis = dehydration, removal of H2O, condensation synthesis- Breakdown == hydrolysis, add waterCarbohydratesSugars are composed of carbon, hydrogen and oxygen, generally multiplesof CH2O.Sugars and starches are composed of repeating sugar molecules;they may range form 1 to many thousand subunits long, and may be straightchains or branched structures. Sugar monomers are important in energymetabolism and provide building blocks for other molecules. Polymers orstarches are important for storage and structure.- Carbonyl at end = aldose- Carbonyl not at end = ketoseStructures- Ring Structure- Sugars may exist as linear or ring structures. Glucose, a 6 carbon aldosesugar forms a ring with the # 5 carbon and the # 1 carbon bound to the same ring. Thusglucose forms a six-member ring with one oxygen in the ring,and the # 6 carbon forms a “tail”.- Glycoside Linkage- Two sugars may join to form a disaccharide by a Glycoside Linkage.- c - o - c- Maltose = Glucose + Glucose- Sucrose = Glucose + Fructose- Lactose = Glucose + Galactose- Asymmetric Carbon- Different arrangements around an asymmetric carbon may give sugarisomers with different properties, such as glucose and galactose.StarchMany sugars, monomers, joined to form long polymers, joining togetherwith glycoside linkage the 1 carbon of one monomer to the 4 carbon of thenext. This head to tail linkage can repeat to produce very long molecules.Starch is used for storage and structure.- Storage:- Plants: - Amylose - unbranched- Amylopectin - branched- Animal:- Glycogen multi-branched (liver, muscle cells)- Structure:- Plants:- Cellulose– like starch l-4 linked glucose but different geometry for #1 carbon- forms rigid fibers which few organisms candigest, except:- bacteria in cows- protozoa in termites- also some fungi- Animals: - Chitin - Animals and some fungi use Chitinmade of glucose with an aminogroup attached. Some organismsmay incorporate protein, silicon orsulfurLipidsFats, phospholipids and steroids are hydrocarbon compounds C-H- Fatsare made of fatty acids linked to glycerol:- Fats are solid at room temperature- Oils are liquid at room temperatureFatsThree long fatty acid molecules are linked to one glycerol molecule,forming, a triacylglycerol. Fats have more “energy”, calories, thancarbohydrates. Fat is stored in adipose cells.- Saturated fatty acid only single bonds between carbonsanimal fats, solid at room temperaturemolecules can pack together tightly- Unsaturated fatty acid one or more double bonds between carbonsplant and fishes, liquid at room temperaturekinks in carbon chain prevent close packingPhospholipidsFat molecules with 2 fatty acids and 1 phosphate joined to oneglycerol molecule, forming a phospholipid. The phosphate head ispolar or hydrophilic; the fatty acid tail is nonpolar orhydrophobic. In aqueous solutions phospholipids will cluster toform a micelle or phospholipid bilayer. The cell membrane isformed from a lipid bilayer.SteroidsHydrocarbons made from 4 fused rings. Different functional groupsattached to the rings confer different properties. Cholesterol is a commonsteroid. Several important hormones such as testosterone and estradiol aresteroids.ProteinsProteins are composed of Amino Acids linked together.Amino Acid: Amino acids are distinguished by different R groups or side chains. Theserange form simple hydrogen to complex acidic, basic or ring groups.- 20 different R groups give different properties and structure to proteins:- Nonpolar- Polar- Acidic- BasicTo form a protein, amino acids are linked together with a covalent peptidebond, linking the carboxyl group of one amino acid to the amino group ofanother. The resulting chainis termed a polypeptide. Proteins are composed ofone or more polypeptide chains.The shape and function of a protein is determined by the order of amino acids, andhow the polypeptide chain is folded and joined to other chains. Proteins may bemodified by the addition of other groups or atoms.Protein Structure- Primary - order of amino acids- Secondary - regular form the polypeptide chain takes, due tohydrogen bonds between amino and carboxyl- helix - a twisted single-strand chain- p-pleated sheet - folded parallel chains- Tertiary - irregular folding of chain held in place by:o hydrogen bondso hydrophobic interactionso ionic bondso disulfide bridgeo This gives the protein its novel properties- Quaternary - 2 or more chains associated to form more elaborate structure. Many proteins are dimers or multimers of the same subunit. The same forces involved in tertiary structure hold the subunits togetherDenaturationThe peptide chain may unfold and lose its 3-dimensional structure due toheat, ions, nonpolar solvents or other treatments. Some proteins mayreform correctly, most won’t. A boiled egg is the best example.Protein FunctionStructure= collagenStorage = ovalbumin, caseinTransport = hemoglobinContraction = actin, myosinSignal Transduction = hormones, hormone receptors (insulin)Defense = antibodiesChemical reactions = enzymes, trypsinNucleic AcidsNucleotide building blocks are composed of a nitrogenous base, either apurine or pyrimidine linked to a ribose (RNA) sugar or a deoxyribose(DNA) sugar and a phosphate group. Nucleic acids are involved primarilyin the storage and utilization of information. They also play a role incellular structure, regulation and enzyme


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