Cell Structure and Function

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Cell Structure and Function. Cells. Smallest living unit Most are microscopic. Discovery of Cells. Robert Hooke (mid-1600s) Observed sliver of cork Saw “row of empty boxes” Coined the term cell. Cell theory. (1839)Theodor Schwann & Matthias Schleiden - PowerPoint PPT Presentation

Transcript of Cell Structure and Function

  • Cell Structure and Function

  • CellsSmallest living unitMost are microscopic

  • Discovery of CellsRobert Hooke (mid-1600s)Observed sliver of corkSaw row of empty boxesCoined the term cell

  • Cell theory(1839)Theodor Schwann & Matthias Schleiden all living things are made of cells

    (50 yrs. later) Rudolf Virchowall cells come from cells

  • Principles of Cell TheoryAll living things are made of cells

    Smallest living unit of structure and function of all organisms is the cell

    All cells arise from preexisting cells(this principle discarded the idea of spontaneous generation)

  • Cell Size

  • Cells Have Large Surface Area-to-Volume Ratio

  • Characteristics of All CellsA surrounding membraneProtoplasm cell contents in thick fluidOrganelles structures for cell functionControl center with DNA

  • Cell TypesProkaryotic


  • Prokaryotic CellsFirst cell type on earthCell type of Bacteria and Archaea

  • Prokaryotic CellsNo membrane bound nucleusNucleoid = region of DNA concentrationOrganelles not bound by membranes

  • Eukaryotic CellsNucleus bound by membraneInclude fungi, protists, plant, and animal cellsPossess many organellesProtozoan

  • Representative Animal Cell

  • Representative Plant Cell

  • OrganellesCellular machinery Two general kindsDerived from membranesBacteria-like organelles

  • Bacteria-Like OrganellesDerived from symbiotic bacteria

    Ancient association

    Endosymbiotic theoryEvolution of modern cells from cells & symbiotic bacteria

  • Plasma MembraneContains cell contentsDouble layer of phospholipids & proteins

  • PhospholipidsPolarHydrophylic headHydrophobic tail

    Interacts with water

  • Movement Across the Plasma MembraneA few molecules move freelyWater, Carbon dioxide, Ammonia, Oxygen

    Carrier proteins transport some moleculesProteins embedded in lipid bilayerFluid mosaic model describes fluid nature of a lipid bilayer with proteins

  • Membrane Proteins1. Channels or transportersMove molecules in one direction2. Receptors Recognize certain chemicals

  • Membrane Proteins3. Glycoproteins Identify cell type4. Enzymes Catalyze production of substances

  • Cell WallsFound in plants, fungi, & many protistsSurrounds plasma membrane

  • Cell Wall DifferencesPlants mostly celluloseFungi contain chitin

  • CytoplasmViscous fluid containing organelles components of cytoplasmInterconnected filaments & fibers Fluid = cytosolOrganelles (not nucleus) storage substances

  • CytoskeletonFilaments & fibers

    Made of 3 fiber typesMicrofilamentsMicrotubulesIntermediate filaments 3 functions: mechanical support anchor organelles help move substances

  • A = actin, IF = intermediate filament, MT = microtubule

  • Cilia & FlagellaProvide motilityCilia ShortUsed to move substances outside human cellsFlagella Whip-like extensionsFound on sperm cells Basal bodies like centrioles

  • Cilia & Flagella StructureBundles of microtubulesWith plasma membrane

  • CentriolesPairs of microtubular structuresPlay a role in cell division

  • Membranous OrganellesFunctional components within cytoplasmBound by membranes

  • Nucleus Control center of cell

    Double membrane

    Contains ChromosomesNucleolus

  • Nuclear EnvelopeSeparates nucleus from rest of cell

    Double membrane

    Has pores

  • DNAHereditary material

    ChromosomesDNAProtiensForm for cell division Chromatin

  • NucleolusMost cells have 2 or moreDirects synthesis of RNAForms ribosomes

  • Endoplasmic ReticulumHelps move substances within cells

    Network of interconnected membranes

    Two typesRough endoplasmic reticulumSmooth endoplasmic reticulum

  • Rough Endoplasmic ReticulumRibosomes attached to surfaceManufacture protiensNot all ribosomes attached to rough ERMay modify proteins from ribosomes

  • Smooth Endoplasmic ReticulumNo attached ribosomesHas enzymes that help build moleculesCarbohydratesLipids

  • Golgi ApparatusInvolved in synthesis of plant cell wallPackaging & shipping station of cell

  • Golgi Apparatus Function1. Molecules come in vesicles

    2. Vesicles fuse with Golgi membrane

    3. Molecules may be modified by Golgi

  • Golgi Apparatus Function (Continued)4. Molecules pinched-off in separate vesicle

    5. Vesicle leaves Golgi apparatus

    6. Vesicles may combine with plasma membrane to secrete contents

  • LysosomesContain digestive enzymesFunctions Aid in cell renewalBreak down old cell parts Digests invaders

  • VacuolesMembrane bound storage sacsMore common in plants than animalsContents WaterFoodwastes

  • Bacteria-Like OrganellesRelease & store energy

    Types Mitochondria (release energy) Chloroplasts (store energy)

  • MitochondriaHave their own DNABound by double membrane

  • MitochondriaBreak down fuel molecules (cellular respiration)GlucoseFatty acids

    Release energyATP

  • ChloroplastsDerived form photosynthetic bacteriaSolar energy capturing organelle

  • PhotosynthesisTakes place in the chloroplastMakes cellular food glucose

  • Review of Eukaryotic Cells

  • Review of Eukaryotic Cells

  • Molecule Movement & CellsPassive Transport

    Active Transport

    Endocytosis (phagocytosis & pinocytosis)Exocytosis

  • Passive TransportNo energy required

    Move due to gradientdifferences in concentration, pressure, charge

    Move to equalize gradientHigh moves toward low

  • Types of Passive Transport1. Diffusion

    2. Osmosis

    3. Facilitated diffusion

  • DiffusionMolecules move to equalize concentration

  • OsmosisSpecial form of diffusion

    Fluid flows from lower solute concentration

    Often involves movement of waterInto cellOut of cell

  • Solution Differences & Cells solvent + solute = solutionHypotonicSolutes in cell more than outsideOutside solvent will flow into cellIsotonicSolutes equal inside & out of cellHypertonicSolutes greater outside cellFluid will flow out of cell

  • Facilitated DiffusionDifferentially permeable membrane

    Channels (are specific) help molecule or ions enter or leave the cellChannels usually are transport proteins (aquaporins facilitate the movement of water)No energy is used

  • Process of Facilitated TransportProtein binds with moleculeShape of protein changesMolecule moves across membrane

  • Active TransportMolecular movementRequires energy (against gradient)Example is sodium-potassium pump

  • EndocytosisMovement of large materialParticlesOrganisms Large moleculesMovement is into cells Types of endocytosis bulk-phase (nonspecific) receptor-mediated (specific)

  • Process of EndocytosisPlasma membrane surrounds materialEdges of membrane meetMembranes fuse to form vesicle

  • Forms of EndocytosisPhagocytosis cell eatingPinocytosis cell drinking

  • ExocytosisReverse of endocytosisCell discharges material

  • ExocytosisVesicle moves to cell surfaceMembrane of vesicle fuses Materials expelled