download UNIT II – CELL STRUCTURE & FUNCTION Chpts 6-8 & 11

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Transcript of UNIT II – CELL STRUCTURE & FUNCTION Chpts 6-8 & 11


    Chpts 6-8 & 11

  • I. DISCOVERY OF CELLSHistory of Microscopes_____________________________________First to try stacking several lenses together to view tiny objects. Looked at pond water First scientist to describe living cells as seen through a microscope._____________________________________Used the microscope to examine thin slices of cork. He called the tiny boxes he saw cells. He chose the name "cells" because the chambers he saw reminded him of rooms in a monastery which were called cells.Cell Theory

  • I. DISCOVERY OF CELLS, cont.Types of MicroscopesCompound Light Microscope___________________Ratio of an objects image to its real size__________________Measure of clarity of an image

    Electron Microscope__________________ Electron Microscope (SEM)Used to study the surface of the specimen

    __________________ Electron Microscope (TEM)Used to study the internal structure of cellsTEMSEM

  • II. CELL TYPES_________________ CellsTypically smaller than eukaryotes

    BacteriaKingdom Archaebacteria Kingdom Eubacteria

    No true nucleus DNA found as a single chromosome in region called ________________

  • II. CELL TYPESStructure found in all prokaryotic cells_________________________________________________________________________________________________________Additional structures that may be present_______________________________________________________________

  • II. CELL TYPES___________________ CellsLarger, more complexContain true nucleus and membrane-bound organelles suspended in cytosolComposed of NucleusRibosomesEndomembrane SystemERGolgi ApparatusLysosomesVacuolesMitochondria/ChloroplastsPeroxisomesCytoskeleton

  • III. EUKARYOTIC CELL STRUCTURES _____________________Control center of eukaryotic cell Made up of ________________________Double membrane that protects nucleus; continuous with ER Contains _____________ to allow RNA to leave nucleus ________________________Site of ribosome and rRNA production ________________________DNA wrapped in proteinWill condense during cell division to form chromosomes

  • III. EUKARYOTIC CELL STRUCTURES, contEndomembrane System membranes are related either through physical continuity or by the transfer of membrane segments as vesiclesEndoplasmic Reticulum (within the cytoplasm; little net)Interconnected network continuous with nuclear envelopeRough ERSite of __________________________Smooth ER Synthesis of _______________ Metabolism of _________________ ____________________ of drugs & poisons _________________________________Cell postmaster Receives transport vesicles from ER; modifies, stores, and ships products Receiving side is known as the ________ face; shipping side is known as the __________ face

  • III. EUKARYOTIC CELL STRUCTURES, contEndomembrane System, cont ______________________________Sacs containing hydrolytic enzymesUsed for recycling cellular materials, destroying pathogens ______________________________Storage sacPlants typically have large, central vacuole surrounded by membrane called ___________________. Absorbs water and helps plant cell to grow largerSome protists have contractile vacuole to pump out excess water

  • Endomembrane System The endomembrane system plays a key role in the synthesis (and hydrolysis) of macromolecules in the cell.

  • III. EUKARYOTIC CELL STRUCTURES, cont ____________________________Suspended in cytosol or found on rough ER Site of protein production in a cell _____________________________Site of ________________________________ (making of ATP)Contain their own DNA, ribosomesFound in virtually all eukaryotes cellsEnclosed by 2 membranes; inner membrane has folds called _____________ to increase surface area

  • III. EUKARYOTIC CELL STRUCTURES, cont_____________________________Type of plastid that carries out _____________________ by converting solar energy to chemical energy (glucose) Contain membranous system of flattened sacs called _______________ stack is called a _____________Fluid surrounding thylakoids is called ___________ Contains its own DNA, ribosomes

  • III. EUKARYOTIC CELL STRUCTURES, cont ____________________________________Membrane-bound compartments that use O2 to carry out metabolism H2O2 is produced; broken down by enzymes to produce ______ & ______ ____________________________________Provides structural support to cellMore extensive in animal cellsComposed of three types of proteins ___________________________ Thinnest filaments .AKA. ____________ filaments. Bundles of them form microvilli - extensions of the cell membrane found in some cells to increase surface area. Interact with myosin in muscle cells to create movement_________________________________ In between in thickness; more permanent than microtubules/microfilaments. _________________________________ Hollow rods that support cell, serve as tracks for movement within cell. Help separate chromosomes during cell division - occurs in a region called centrosome, which is the location of centrioles in animal cells. Cilia, flagella are constructed from bundles of microtubules covered by extensions of the cell membrane.

  • IV. CELL BOUNDARIESCell WallFound in ___________, _______, ________________, and some _________________FunctionsRigid structure; protects cellMaintains shape of cellsPrevents excess water uptakePlant cell wall_________ - primary componentPectin - Sticky polysaccharide found between cell walls of adjacent cells; found in middle lamellaPlasmodesmata - Perforations between adjacent cell walls that allow for movement of materials from one cell to another

  • IV. CELL BOUNDARIES, contExtracellular MatrixFound in animal cellsHolds cells together, protects & supports cellsAllows for communication between cellsComposed primarily of ______________________ proteins with carbohydrate chains that are covalently-bonded Must abundant glycoprotein in most animals is _____________Intracellular JunctionsTight Junctions Fuses membranes together tightly; prevents leakage of fluidDesmosomes (Anchoring Junctions) Fasten cells together in sheetsGap Junctions Allow for movement of cytoplasm from one cell to another; important in communication between cells

  • IV. CELL BOUNDARIES, cont____________________________Selectively-permeable barrier found in all cellsComposed primarily of _______________________ bilayerFluid Mosaic ModelFluid Not a rigid structure. Organization due to high concentration of water inside & outside cell

  • IV. CELL BOUNDARIES, contProteins - Mosaic Assortment of different proteins embedded in bilayer; determine most of membranes specific functions. Act as channels, pumps, enzymes in metabolism, binding sites, etc_____________ Proteins Embedded in phospholipid layer_____________ Proteins Bound to surface of membraneCarbohydrates ID tags that identify cell. Enable cells to recognize each other and foreign cells. May be bonded to lipids (glycolipids) or proteins (glycoproteins)____________________ Found in animal cells for stability


  • V. CELL TRANSPORT, cont________________ Transport Movement of materials from _______ to ______ concentration. No energy output required.___________________ - Random movement of a substance across membrane down concentration gradient until equilibrium is reached.________________________________________ Passive transport of molecules across cell membrane with the help of transport proteins. Water is polar requires protein channels called aquaporins to move in and out of cell. Glucose also requires protein channels due to size.

  • V. CELL TRANSPORT, contPassive Transport, cont______________ Diffusion of water across a membrane.______________ refers to tendency of cell to gain or lose water. If the solution isIsotonic to the cell Solute concentration is same on both sides of membrane. No net movement of water.Hypertonic to the cell Concentration of solute is greater outside cell water moves in until equilibrium is reached. Cell may shrivel.Hypotonic to the cell Concentration of solute is lower outside cell water moves into cell until equilibrium is reached. Cell may swell to bursting point.

    Water moves towards the high solute concentration!!!!!

  • V. CELL TRANSPORT, contPassive Transport/Osmosis, contOsmoregulation Cells must have mechanism to prevent excess loss, uptake of waterCell wall, contractile vacuole_______________________ Seen in plants; excessive water loss causes cell membrane to pull away from cell wall


  • V. CELL TRANSPORT, cont____________ Transport Movement of materials against concentration gradient. Requires energy output by cellCarrier Proteins Na+ / K+ Pump

  • V. CELL TRANSPORT, contActive Transport, cont_________________ Secretion of biomolecules by fusion of vesicles with cell membrane. Biomolecules spit out._________________ Sucking In. Cell membrane surrounds, engulfs particle or biomolecule, pinches in to form vesicle.______________________ Sucking in food particles______________________ Sucking in fluid dropletsReceptor-mediated Endocytosis Very specific

  • VII. CELL SIGNALINGCoordinates cell activities, developmentInitiates series of responses known as signal transduction pathway. Typically involves 3 steps:________________ Target cells detection of signal molecule due to binding of signal molecule to receptor protein in cell membrane________________ Binding of signaling molecule changes receptor protein; triggers a sequence of events within cell________________ Results in specific cellular response; for example, activation of genes, enzyme catalysis, etc.Cyclic AMP Intrac