BIO 198 Cincinnati State

Week # 8 Lecture pp 15-128Lecture Presentations for Integrated Biology and Skills for Success in ScienceBanks, Montoya, Johns, & Eveslage

Cells and Their Membranes By the end of the lecture today, students will be able to:State the cell theoryDefine cell biologyDescribe the different classes of cells in the human bodyDescribe the functions of the plasma membraneDescribe the components of the plasma membrane and explain the role of each component, including lipids and proteinsDifferentiate between microvilli, cilia and flagellum

2Modern Cell TheoryAll organisms are composed of cells and cell productsCell is the simplest structural and functional unit of lifecells are aliveAn organisms structure and functions are due to the activities of its cellsCells come only from preexisting cells, not from nonliving mattertherefore, all life traces its ancestry to the same original cellsCells of all species have many fundamental similarities in their chemical composition and metabolic mechanismsCell biology study of cells (i.e., their morphology, physiological properties, organelles, interactions with the environment, life cycles, division and death)

http://www.youtube.com/watch?v=4OpBylwH9DU Cell Shapes about 200 types of cells in the human bodySquamous - thin and flat with nucleus creating bulgePolygonal - irregularly angular shapes with 4 or more sidesStellate starlike shapeCuboidal squarish and about as tall as they are wideColumnar - taller than wideSpheroid to Ovoid round to ovalDiscoid - disc-shapedFusiform - thick in middle, tapered toward the endsFibrous threadlike shapeNote: some of these shapes are cell appearance in tissue sections, but not their 3 dimensional shapeCell Shapes

SquamousPolygonalCuboidalColumnarSpheroidDiscoidFusiform (spindle-shaped)StellateFibrousTwo Classes of cells in the Human BodySex cells, also known as germ cells or reproductive cells, are either sperm cells of males or oocyte cells of females.Somatic cells are the cells that make up everything else in the body.Cell SizeHuman cell sizemost from 10 - 15 micrometers (m) in diameteregg cells (very large)100 m diameterbarely visible to the naked eyenerve cell at 1 meter longlongest human celltoo slender to be seen with naked eyeLimitations on cell sizecell growth increases volume more than surface areasurface area of a cell is proportional to the square of its diametervolume of a cell is proportional to the cube of its diameternutrient absorption and waste removal utilize surface areaif cell becomes too large, may rupture like overfilled water balloonhttp://projects.cbe.ab.ca/ict/udlsci/udlscience/biology/cells/saVol/notes/saVol.htm Major Constituents of Cellplasma (cell) membranesurrounds cellmade of proteins and lipidscomposition and function can vary from oneregion of the cell to another

cytoplasmorganellescytoskeletoncytosol (intracellularfluid - ICF)

extracellular fluid ECFfluid outside of cell

Apical cell surfaceMicrofilamentsSecretory vesicleundergoingexocytosisGolgi vesiclesGolgi complexLateral cell surfaceIntermediate filamentLysosomeRough endoplasmicreticulumSmooth endoplasmicreticulumMicrotubulePlasma membranesBasementmembraneBasal cell surfaceFree ribosomesMitochondrionNucleolusNuclearenvelopeNucleusIntercellularspaceCentrosomeCentriolesSecretory vesicleDesmosomeFat dropletHemidesmosomeTerminal webMicrovillusPlasma Membraneunit membrane forms the border of the cell and many of its organelles-appears as a pair of dark parallel lines around cell (viewed with the electron microscope)plasma membrane unit membrane at cell surface-defines cell boundaries-governs interactions with other cells-controls passage of materials in and out of cell-intracellular face side that faces cytoplasm-extracellular face side that faces outward

(a)Nuclear envelopeNucleusPlasma membraneof upper cellPlasma membraneof lower cellIntercellular space100 nm..Membrane Lipids98% of molecules in plasma membrane are lipids

Phospholipids75% of membrane lipids are phospholipidsamphiphilic molecules arranged in a bilayerhydrophilic phosphate heads face water on each side of membrane hydrophobic tails directed toward the center, avoiding waterdrift laterally from place to placemovement keeps membrane fluid

Plasma MembraneOily film of lipids with diverse proteins embeddedExtracellularface ofmembraneIntracellularface ofmembrane(b)PeripheralproteinExtracellular fluidGlycolipidGlycoproteinCarbohydratechainsTransmembraneproteinPeripheralproteinChannelIntracellular fluidCholesterolProteins ofcytoskeletonPhospholipidbilayerMembrane Protein Functionsreceptors, second-messenger systems, enzymes, ion channels, carriers, cell-identity markers, cell-adhesion molecules

ChemicalmessengerBreakdownproductsIonsCAM ofanother cell(a) Receptor A receptor that binds to chemical messengers such as hormones sent by other cells(b) EnzymeAn enzyme thatbreaks downa chemicalmessenger andterminates itseffect(c) Ion ChannelA channel proteinthat is constantlyopen and allowsions to passinto and out ofthe cell(d) Gated ion channelA gated channelthat opens andcloses to allowions throughonly at certaintimes(e) Cell-identity markerA glycoproteinacting as a cell-identity markerdistinguishing thebodys own cellsfrom foreign cells(f) Cell-adhesionmolecule (CAM)A cell-adhesionmolecule (CAM)that binds onecell to another.http://www.youtube.com/watch?v=y31DlJ6uGgE

Extensions of membrane (1-2 m)serves to increase cells surface areabest developed in cells specialized in absorptiongives 15 40 times more absorptive surface area

on some cells they are very dense and appear as a fringe brush bordermilking action of actinactin filaments shorten microvillipushing absorbed contents down into cellMicrovilliMicrovilliActin microfilaments are found in center of each microvilli.

(a)1.0m(b)0.1GlycocalyxActinmicrofilamentsMicrovillus..mCiliaHairlike processes 7-10m longsingle, nonmotile primary cilium found on nearly every cellantenna for monitoring nearby conditionssensory in inner ear, retina, nasal cavity, and kidney

Motile cilia respiratory tract, uterine tubes, ventricles of the brain, efferent ductules of testesbeat in wavessweep substances across surface in same directionpower strokes followed by recovery strokes

(a)MucusSalinelayerEpithelialcells1234567Power strokeRecovery stroke(b).Structure of Cilia

Cilia(a)10 m..http://www.youtube.com/watch?v=dXVG-DwOtKU Flagella tail of the sperm - only functional flagellum

whiplike structure with axoneme identical to ciliummuch longer than ciliumstiffened by coarse fibers that supports the tail

movement is more undulating, snakelikeno power stroke or recovery stroke as in cilia

Exit Quiz1). Name the three fundamental parts of the cell theory and identify who introduced each of these parts to the scientific community.2). Why are the majority of cells observed to be so small?3). What are the major components to a cell? What are the primary functions of each of these components? 4). What are the seven major functions of proteins in a cell membrane?5). What are the fundamental differences between cilia and flagella?