Cell theoryCell is basic structural and functional unit of living organismsActivities of organs depend on both individual and collective activity of its cellsBiochemical activities of cells are dictated by their shape/forms, and by relative # of their specific subcellular structureContinuity of life from one generation to another has a cellular basis200 different types of cellsHuman cell has 3 main componentsPlasma membraneCytoplasmNucleusPlasma membraneDefines extent of cellSeparates intracellular fluids, and extracellular fluidMembrane lipidsLipid bilayer: basic fabricPhospholipids, glycolipids, cholesterol, lipid raftPhospholipidsMake up 75% of membraneLollipop shapedHead=polar and is hydrophilic (water loving)Tail= uncharged and hydrophobic (water fear)Because of the water loving/fear all plasma membranes share a sandwich like structureMostly unsaturated (only single bonds)This kinks their tails (increases space between) and increases membrane fluidityNonpolar/polar interaction prevents them from moving aroundGlycolipids5% of total membraneLipids with sugar groups attachedFound only on outer plasma membrane surfaceSugar groups make the end of the glycolipid polarCholesterol20% membrane lipidWedges plate like hydrocarbon rings between phospholipid tails, stabilizing the membrane and decreasing mobility of the phospholipids and fluidity of membraneMembrane proteins50% of membrane massIntegral proteinsFirmly inserted in lipid bilayerBoth hydrophobic and hydrophilic regionsAllows them to interact with water in and out of the cellCan act as channels (for small molecules) or carriers (for substances) can pass throughSome are receptors for hormones and relay messagesPeripheral proteinsNot in lipid bilayerAttached to integral proteinsEasily removedEnzymes, motor proteins, cell linking, helps intracellular supportLipid rafts20% of cell membranePhospholipids, sphingolipids, cholesterolCan include/exclude specific proteinsStable platform for certain receptorsMore stable and less fluid than rest of membraneGlycocalyxCells identify each other by thisCell junctionsTight Junctions: help prevent molecules from passing throughImpermeableIntegral proteins fuse togetherDesmosomes: anchoring junctionsCytoplasmic side there is a “plague”Abundant in tissues with great mechanical stressCadherin’s (linker proteins) act as VelcroDistributes tensionGap Junctions: communication junctionsIons, simple sugars, and small molecules pass through herePresent in electrically excitable tissuesConnexons form channelMembrane transportSelectively permeablePassiveNo energy requiredActiveCell provides metabolic energyUsually ATPPassiveDiffusion and filtrationDiffusionMoves from higher concentration to lower concentrationConcentration gradientDriving force is kinetic energySmall, warm molecules is the fastest for diffusionSimple diffusionNonpolar and lipid soluble substances diffuse directly through the lipid bilayerOxygen, carbon dioxide, and fat soluble vitaminsFacilitated diffusionSubstance either binds to protein carriers and is ferried across or moves through water filled protein channelsGlucose, amino acids, ionsCarrier meditated facilitated diffusionIntegral proteinsUsed for molecules to big for channelsPolar moleculesBinding of substrate cause change in shape of carrierWhen all carriers are “engaged” they are said to be saturatedChannel meditated facilitated diffusionTrans membrane proteins that transport substance through aqoues channels from one end of the membrane to the otherSelective due to pore sizeLeakage channelsAlways openAllows water/ions and moves according to concentration gradientGated channelsControlled by chemical/electrical signalsOsmosisDiffusion of water through selectively permeable membraneThrough lipid bilayerThrough water channels aquaporin’sOsmolality: total concentration of solute particlesTonicityDepends on solute concentration and solute permeability of plasma membraneCytoplasmCellular material between membranes and nucleusIncludes cytosol, organelles, and inclusionsCytosolViscous, semi transparent fluid in which the other cytoplasmic elements are suspendedOrganellesMetabolic machinery of the cellInclusionsChemical substancesStored nutrients (glycogen granules in liver, liquid droplets in fat cells, pigment in hair, crystals in various cellsOrganelles:Non membranous:CytoskeletonCentriolesRibosomesMembranous:MitochondriaPeroxisomesLysosomesEndoplasmic reticulumGolgi apparatusMitochondriaPower plant of cell2 membranesInner “shelf like cristae”OuterProvides most of cells ATP through aerobic cellular respirationBecause it requires oxygenContain own DNA, RNA and ribosomes are able to reproduce themselvesWhen more ATP is required mitochondria synthesize more cristae or simply pinch in half “fission”RibosomesSmall dark staining granulesComposed of protein and RNA2 globular subunitsFree ribosomesFloating freelySoluble proteinsMembrane bound ribosomesRough Endoplasmic reticulumSynthesize proteins destined for incorporation into the cell membrane or lysosomesEndoplasmic reticulumInterconnected tubes and parallel membranes enclosing fluid50% of cell membraneRough endoplasmic reticulumStudded with ribosomesMakes all proteins secreted from the cellSynthesize membrane integral proteins and phospholipidsSmooth endoplasmic reticulumTubes arranged in looping networkIn liver: lipid and cholesterol metabolism breakdown of glycogen, and along with kidneys, detoxification of drugs, pesticides, and carcinogensSynthesis of steroid based hormonesIn intestinal cells- absorption, synthesis, and transport of fatSkeletal and cardiac muscle: storing and releasing calciumGolgi ApparatusStacked and flattened membranous sacsModify concentrate, and package proteins and lipidsTransport vessels from ER fuse with convex cis face of Golgi apparatus (receiving)Proteins then pass through trans faceSecretory vesicles leave their trans face (shipping) of Golgi stack and move to designated parts of cellsLysosomesDigest foreign substancesSpherical membranous bags containing digestive enzymesWorks best in acidic conditionsDispose of invading bacteria and cell debrisDisregards non functioning organellesPreforms metabolic functions (glycogen breakdown and release)Breaks down bone to release calcium ion into the bloodDestroys cell in injured or non useful tissuePeroxisomeMembranous sac containing powerful oxidases and catalaseDetoxifies harmful and toxic substancesNeutralize dangerous free