A preview of the cellThe cell is the fundamental structural and functional unit of a living organism; it has a limiting boundary (ADD)All cells store their genetic material in the same linear chemical code (DNA)All cells replicate, transcribe, and translate their genetic material by templated polymerization (DNA > RNA > Protein)All cells transcribe portions of their genetic information into the same intermediary form (RNA)Differences among cellsNuclearOuter boundary (ADD)Tagging microscopy- locatingProkaryotes- small size, by the absencePlasmids carry antibiotic resistanceProkaryotes have a cell wall outside the cell membrane composed of carbohydrates (sugars) linked to proteins and are called (ADD)Cell wall made of celluloseThe membraneWater polar side, fatty acid nonpolar sideFreeze fracture- splits membraneNucleous- site of ribosomal synthesisMitochondrian-Ribosomes-Rough ER- with ribosomesGolgi Apparatus-CytoskeletonMicrotubules- cross members to maintain structureMicrofilaments- two intertwined strands of actin (responsible for muscle contractions), steel beams for structureIntermediate filaments- fibrous proteins supercoiled into thicker cablesSummary of cell componentsNucleusVacuolesMitochondriaChloroplastsCytoskeletonPlasma membraneCell wallLectureThe cell is the fundamental structural and functional unit of a living organism; it has a limiting boundary (membrane) and contains templated genetic information and can replicate by itselfMolecules in the cellWaterCarbohydrates C(H2O)nC6H12O6(ADD)Atomic configurationElectrons- atomic numberProtons- atomic numberNeutrons- plus protons=atomic massIsotopes- same atomic number different atomic massValence shells- where the chemistry is done (outer shell)Chemical bondsCovalent bondsElectron sharing between atomsStrong and stableNoncovalent bondsAttraction through electrostatic interactions or hydrophobic interactionsMay be strong, but generally weaker than covalent bondsGenerally less stable than covalent bondsElectron sharingNot always equal in covalent bondsSome atoms pull electrons harder than othersElectronegativity- electrons are pulled towards the more electronegative member of the pair–C-C: equal sharing–C-H: nearly equal sharing–O-H: very near equal sharing (ADD), Polar Covalent BondElectrons have the greatest potential energy in the outermost electron shellsWaterPolar molecule- electrons are pulled toward oxygenHydrogen bonds form between water moleculesProperties of waterHigh heat of absorption (1cal/gm/C)Heat of Vaporization (1 gm at 25 degrees=580 cal)Maximum density at 4CHigh dielectric constantWhy is water so special?Each molecule can H-bond with 4 other moleculesProvides significant structure to water in all physical phasesAcids and basesAcid- increases the number of H+ in the solutionBase- decreases the number of H+ in the solutionUse pH scale to measure [H+] in solutionpH= -log10[H+]pH of pure water= -log10 10^-7=7.0pH scale goes from 0-14The pH scalepH is the negative log of the H ion concentrationLog scaleEach point represents a 10x difference in [H+]Structure of carbonThe most common isotope of carbon has 6 electrons, 6 protons, and 6 neutrons4 electrons in outer (valence) shellCan become very stable in a molecule by sharing 4 electronsCarbon is intersection that can branch up to 4 times (bonds)Molecular diversity: carbon isomersStructural isomersDiffer in covalent arrangement of atomsGeometric isomersCis vs. trans arrangement around a C=CEnantiomersOrientation of atoms around an asymmetric carbonProduces mirror-image moleculesImportance of structure-function relationshipEnantiomers reveal the importance of structure to functionDopamine used to treat Parkinson’sL form is active; D form is notHydrocarbonsMolecules consisting of only H and CCan be very diverse in structureMay be important in biology, but generally of limited usefulnessRelatively inertNonpolarInsoluble in aqueous solutionsFunctional groupsSmall organic groups that impart chemical reactivity to hydrocarbonsTake place of one or more Hs in a molecule6 common functional groupsHydroxyl (-OH)Carbonyl (>C=O)Amino (-NH2)Sulfhydryl (-SH)Phosphoryl (-O-HO OH-P=O)Functional groups increase chemical reactivity of organic moleculesMake hydrocarbons more reactiveDonate or accept protonsDonate or accept electronsMay become ionizedMake hydrocarbons more polarMake hydrocarbons more solubleMake hydrocarbons more interesting biologicallyMolecules in the cellWaterCarbohydrates (CH20)nC6H12O6LipidsProteinsNucleic AcidsTrace mineralsMacromoleculesLarge molecules built by the successive addition of smaller moleculesPolymersPolysaccharides, proteins, and Nucleic acids are called Polymers (Lipids could be considered polymers of acetic acid)Built from successive addition of smaller subunits called MonomersIn any given polymer, subunits are identical or very similarAll polymers are built from fewer than 50 monomersMacromolecular SynthesisMacromolecules differ in the structure of the monomersAre synthesized and broken down by the same general mechanismPolymer synthesisOne molecule of H2O released for every monomer added to the polymerDehydrationPolymer disassemblyOne molecule of H2O added for every monomer removed from the polymerHydrolysisCarbohydratesEnergy storage, protection, recognition, and structural integrityCarbohydrates are literally “hydrates of carbon”Molecules which the general formula of (CH2O)n(CH20)6=C6H12O6Carbohydrates are sugars and their polymersClassified in a number of waysTrioeses (3 carbons)Pentoses (5 carbons)Hexoses (6 carbons)All carbohydrates end in –oseFinally, carbohydrates can be classified by their functional group intoAldoses- carbonyl on a terminal carbon (glucose)Ketoses- carbonyl on an internal carbon (fructose)Carbonyl-Classified by the number of monomer unitsMonosaccharidesDisaccaridesPolysaccharidesThree ways of classifying carbohydratesCommon structural featuresCarbonyl group- >C=OLots of hydroxl groups- -OHMakes carbohydrates very polarMakes carbohydrates very soluble in aqueous solutionsStructure of glucoseRing form is common in aqueous solutionsColvalent attachment of monosaccharidesColvalent bond termed a Glycosidic LinkageFormed by Dehydration SynthesisPolysaccharide can contain hundreds to thousands of monosaccharidesFunctions of polysaccharidesEnergy storageStructureEnergy storage: plantsStarchPolymer of a-GlucoseBranched or unbranchedStored in plastids (Chloroplasts)Helical structureEnergy storage:
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