1. CAMPBELLBIOLOGYReece Urry Cain Wasserman Minorsky Jackson 2014 Pearson Education, Inc.TENTHEDITION6A Tour ofthe CellLecture Presentation byNicole Tunbridge andKathleen Fitzpatrick

2. The Fundamental Units of Life All organisms are made of cells The cell is the simplest collection of matterthat can be alive All cells are related by their descent from earliercells Cells can differ substantially from one another butshare common features 2014 Pearson Education, Inc. 3. Figure 6.1 2014 Pearson Education, Inc. 4. Concept 6.1: Biologists use microscopes andthe tools of biochemistry to study cells Cells are usually too small to be seen by thenaked eye 2014 Pearson Education, Inc. 5. Microscopy Microscopes are used to visualize cells In a light microscope (LM), visible light is passedthrough a specimen and then through glass lenses Lenses refract (bend) the light, so that the imageis magnified 2014 Pearson Education, Inc. 6. Three important parameters of microscopy Magnification, the ratio of an objects imagesize to its real size Resolution, the measure of the clarity of the image,or the minimum distance of two distinguishablepoints Contrast, visible differences in brightness betweenparts of the sample 2014 Pearson Education, Inc. 7. Figure 6.2 2014 Pearson Education, Inc.10 m1 m0.1 m1 cm1 mm100 m10 m1 m100 nm10 nm1 nmHuman heightLength of somenerve andmuscle cellsChicken eggFrog eggHuman eggMost plant andanimal cellsNucleusMost bacteriaMitochondrionSmallest bacteriaVirusesRibosomesProteinsLipidsSmall molecules0.1 nm AtomsUnaided eyeLMEMSuper-resolutionmicroscopy 8. Figure 6.2a10 m1 m0.1 m1 cm1 mm100 m 2014 Pearson Education, Inc.Human heightLength of somenerve andmuscle cellsChicken eggFrog eggHuman eggUnaided eyeLM 9. Figure 6.2b100 m10 m1 m100 nm10 nm1 nmNucleusMost bacteriaMitochondrionSmallest bacteriaVirusesRibosomesProteinsLipids0.1 nm Atoms 2014 Pearson Education, Inc.Small moleculesLMSuper-resolutionmicroscopyEMMost plant andanimal cells 10. Figure 6.2cUnaided eye 2014 Pearson Education, Inc.Electron microscopyLight microscopySuper-resolutionmicroscopyHumanheightLengthof somenerveandmusclecellsChickeneggFrogeggHumaneggNucleusMostplantandanimalcellsMostbacteriaMito-chondrionSmallestbacteriaVirusesRibo-somesProteinsLipidsSmallmoleculesAtoms10 m 1 m 0.1 m 1 cm 1 mm 100 m 10 m 1 m 100 m 10 nm 1 nm 0.1 nm 11. Light microscopes can magnify effectively to about1,000 times the size of the actual specimen Various techniques enhance contrast and enablecell components to be stained or labeled The resolution of standard light microscopy is toolow to study organelles, the membrane-enclosedstructures in eukaryotic cells 2014 Pearson Education, Inc. 12. Figure 6.3 2014 Pearson Education, Inc.50 m10 m50 m10 m1 m2 m 2 mBrightfield(unstainedspecimen)Brightfield(stained specimen)Phase-contrast Differential-interference-contrast(Nomarski)Fluorescence Confocal (without) Confocal (with)DeconvolutionSuper-resolution(without)Super-resolution(with)Scanningelectronmicroscopy (SEM)Transmissionelectronmicroscopy (TEM) 13. Figure 6.3aLight Microscopy (LM) 2014 Pearson Education, Inc.Brightfield(unstained specimen)Brightfield(stained specimen)Phase-contrast Differential-interference-contrast(Nomarski)50 m 14. Figure 6.3aaBrightfield (unstained specimen)50 m 2014 Pearson Education, Inc. 15. Figure 6.3ab 2014 Pearson Education, Inc.Brightfield(stained specimen)50 m 16. Figure 6.3acPhase-contrast50 m 2014 Pearson Education, Inc. 17. Figure 6.3ad 2014 Pearson Education, Inc.Differential-interference-contrast(Nomarski)50 m 18. Figure 6.3b 2014 Pearson Education, Inc.Light Microscopy (LM)FluorescenceDeconvolutionConfocal (without) Confocal (with)10 m10 m50 m 19. Figure 6.3ba 2014 Pearson Education, Inc.Fluorescence10 m 20. Figure 6.3bb 2014 Pearson Education, Inc.Deconvolution10 m 21. Figure 6.3bc 2014 Pearson Education, Inc.Confocal (without)50 m 22. Figure 6.3bd 2014 Pearson Education, Inc.Confocal (with)50 m 23. Figure 6.3cLight Microscopy (LM)Super-resolution (without) 2014 Pearson Education, Inc.1 mSuper-resolution (with)Scanningelectronmicroscopy (SEM)Transmissionelectronmicroscopy (TEM)Electron Microscopy (EM)2 m 2 m 24. Figure 6.3ca 2014 Pearson Education, Inc.1 mSuper-resolution (without) 25. Figure 6.3cb 2014 Pearson Education, Inc.1 mSuper-resolution (with) 26. Figure 6.3cc 2014 Pearson Education, Inc.Scanningelectronmicroscopy (SEM)2 m 27. Figure 6.3cd 2014 Pearson Education, Inc.Transmissionelectronmicroscopy (TEM)2 m 28. Two basic types of electron microscopes (EMs)are used to study subcellular structures Scanning electron microscopes (SEMs) focus abeam of electrons onto the surface of a specimen,providing images that look 3-D Transmission electron microscopes (TEMs)focus a beam of electrons through a specimen TEMs are used mainly to study the internalstructure of cells 2014 Pearson Education, Inc. 29. Recent advances in light microscopy Confocal microscopy and deconvolution microscopyprovide sharper images of three-dimensionaltissues and cells New techniques for labeling cells improve resolution 2014 Pearson Education, Inc. 30. Cell Fractionation Cell fractionation takes cells apart andseparates the major organelles from one another Centrifuges fractionate cells into theircomponent parts Cell fractionation enables scientists to determinethe functions of organelles Biochemistry and cytology help correlate cellfunction with structure 2014 Pearson Education, Inc. 31. Figure 6.4 2014 Pearson Education, Inc.HomogenateHomogenizationTissuecellsCentrifugationSupernatant 1,000 g poured into next tube10 min20,000 g20 min80,000 g60 min150,000 g3 hrPellet rich inribosomesPellet rich inmitochondriaand chloroplastsPellet rich inmicrosomesPellet rich innuclei andcellular debrisDifferentialcentrifugation 32. Figure 6.4a 2014 Pearson Education, Inc.HomogenateHomogenizationTissuecellsCentrifugation 33. Figure 6.4b1,000 g10 min 2014 Pearson Education, Inc.Supernatant poured into next tube20,000 g20 min80,000 g60 min150,000 g3 hrPellet rich inribosomesPellet rich inmitochondriaand chloroplastsPellet rich inmicrosomesPellet rich innuclei andcellular debrisDifferentialcentrifugation 34. Concept 6.2: Eukaryotic cells haveinternal membranes that compartmentalizetheir functions The basic structural and functional unit of everyorganism is one of two types of cells: prokaryoticor eukaryotic Only organisms of the domains Bacteria andArchaea consist of prokaryotic cells Protists, fungi, animals, and plants all consist ofeukaryotic cells 2014 Pearson Education, Inc. 35. Comparing Prokaryotic and Eukaryotic Cells Basic features of all cells Plasma membrane Semifluid substance called cytosol Chromosomes (carry genes) Ribosomes (make proteins) 2014 Pearson Education, Inc. 36. Prokaryotic cells are characterized by having No nucleus DNA in an unbound region called the nucleoid No membrane-bound organelles Cytoplasm bound by the plasma membrane 2014 Pearson Education, Inc. 37. Figure 6.5Bacterialchromosome 2014 Pearson Education, Inc.FimbriaeNucleoidRibosomesPlasma membraneCell wallCapsuleFlagellaA typicalrod-shapedbacterium(a)0.5 mA thin section throughthe bacterium Bacilluscoagulans (TEM)(b) 38. Figure 6.5aNucleoidRibosomesPlasma membraneCell wall 2014 Pearson Education, Inc.Capsule0.5 mA thin section through the bacteriumBacillus coagulans (TEM)(b) 39. Eukaryotic cells are characterized by having DNA in a nucleus that is bounded by amembranous nuclear envelope Membrane-bound organelles Cytoplasm in the region between the plasmamembrane and nucleus Eukaryotic cells are generally much larger thanprokaryotic cells 2014 Pearson Education, Inc. 40. The plasma membrane is a selective barrier thatallows sufficient passage of oxygen, nutrients, andwaste to service the volume of every cell 2014 Pearson Education, Inc. 41. Figure 6.6Outside of cell (a) TEM of a plasma membraneInsideof cell Carbohydrate side chainsHydrophilicregionHydrophobicregionHydrophilicregion 2014 Pearson Education, Inc.Phospholipid Proteins(b) Structure of the plasma membrane0.1 m 42. Figure 6.6a 2014 Pearson Education, Inc.Outside of cellInsideof cell 0.1 m 43. Metabolic requirements set upper limits on thesize of cells The surface area to volume ratio of a cell is critical As a cell increases in size, its volume growsproportionately more than its surface area 2014 Pearson Education, Inc. 44. Figure 6.7 2014 Pearson Education, Inc.Surface area increases whiletotal volume remains constantTotal surface area[sum of the surface areas(height width) of all boxsides number of boxes]5116150 7501 125 1256 1.26Total volume[height width length number of boxes]Surface-to-volume(S-to-V) ratio[surface area volume] 45. A Panoramic View of the Eukaryotic Cell A eukaryotic cell has internal membranes thatpartition the cell into organelles The basic fabric of biological membranes is adouble layer of phospholipids and other lipids Plant and animal cells have most of the sameorganelles 2014 Pearson Education, Inc. 46. Figure 6.8a 2014 Pearson Education, Inc.FlagellumCentrosomeCYTOSKELETON:MicrofilamentsIntermediate filamentsMicrotubulesMicrovilliPeroxisomeMitochondrionLysosomeNUCLEUSPlasmamembraneNuclearenvelopeNucleolusChromatinRibosomesGolgi apparatusENDOPLASMICRETICULUM (ER)Rough ER Smooth ER 47. Figure 6.8bNUCLEUSNuclearenvelopeNucleolusChromatinGolgiapparatusMitochondrionPeroxisomePlasmamembrane 2014 Pearson Education, Inc.Rough ERSmooth ERRibosomesCentral vacuoleMicrofilamentsMicrotubulesCYTOSKELETONChloroplastPlasmodesmataCell wallWall of adjacent cell 48. Figure 6.8cAnimal Cells 2014 Pearson Education, Inc.Fungal CellsPlant CellsUnicellularEukaryotesHuman cells from liningof uterus (colorized TEM)Yeast cells budding(colorized SEM)A single yeast cell(colorized TEM)Cells from duckweed(colorized TEM)Chlamydomonas(colorized SEM)NucleusNucleolusChloroplastChlamydomonas(colorized TEM)CellNucleusNucleolusParentcellBudsCell wallVacuoleNucleusMitochondrionCellCell wallChloroplastMitochondrionNucleusNucleolusFlagellaVacuoleCell wall10 m5 m5 m1 m8 m1 m 49. Figure 6.8ca 2014 Pearson Education, Inc.CellNucleusNucleolusHuman cells from liningof uterus (colorized TEM)10 m 50. Figure 6.8cb 2014 Pearson Education, Inc.Yeast cells budding(colorized SEM)ParentcellBuds5 m 51. Figure 6.8cc 2014 Pearson Education, Inc.1 mA single yeast cell(colorized TEM)Cell wallVacuoleNucleusMitochondrion 52. Figure 6.8cd 2014 Pearson Education, Inc.Cells from duckweed(colorized TEM)CellCell wallChloroplastMitochondrionNucleusNucleolus5 m 53. Figure 6.8ce 2014 Pearson Education, Inc.8 mChlamydomonas(colorized SEM) 54. Figure 6.8cfNucleusNucleolusChloroplastChlamydomonas (colorized TEM) 2014 Pearson Education, Inc.FlagellaVacuoleCell wall1 m 55. BioFlix: Tour of a Plant Cell 2014 Pearson Education, Inc. 56. BioFlix: Tour of an Animal Cell 2014 Pearson Education, Inc. 57. Concept 6.3: The eukaryotic cells geneticinstructions are housed in the nucleus andcarried out by the ribosomes The nucleus contains most of the DNA in aeukaryotic cell Ribosomes use the information from the DNA tomake proteins 2014 Pearson Education, Inc. 58. The Nucleus: Information Central The nucleus contains most of the cells genes andis usually the most conspicuous organelle The nuclear envelope encloses the nucleus,separating it from the cytoplasm The nuclear membrane is a double membrane;each membrane consists of a lipid bilayer 2014 Pearson Education, Inc. 59. Figure 6.91 m Nucleus 2014 Pearson Education, Inc.NucleolusChromatinNuclear envelope:Inner membraneOuter membraneNuclear poreNucleusRoughERChromatinNuclear lamina (TEM)Close-upof nuclearenvelopeRibosomePore complexes (TEM)0.25 mPorecomplex0.5 mSurface ofnuclear envelope(TEM) 60. Figure 6.9a 2014 Pearson Education, Inc.NucleolusChromatinNuclear envelope:Inner membraneOuter membraneNuclear poreNucleusRoughERChromatinPorecomplexRibosomeClose-upof nuclearenvelope 61. Figure 6.9b1 m 2014 Pearson Education, Inc.Nuclear envelope:Inner membraneOuter membraneNuclear poreSurface of nuclear envelope(TEM) 62. Figure 6.9c 2014 Pearson Education, Inc.Pore complexes (TEM)0.25 m 63. Figure 6.9d 2014 Pearson Education, Inc.Nuclear lamina (TEM)0.5 m 64. Pores regulate the entry and exit of moleculesfrom the nucleus The nuclear size of the envelop is lined by thenuclear lamina, which is composed of proteinsand maintains the shape of the nucleus 2014 Pearson Education, Inc. 65. In the nucleus, DNA is organized into discreteunits called chromosomes Each chromosome is composed of a single DNAmolecule associated with proteins The DNA and proteins of chromosomes aretogether called chromatin Chromatin condenses to form discretechromosomes as a cell prepares to divide The nucleolus is located within the nucleus and isthe site of ribosomal RNA (rRNA) synthesis 2014 Pearson Education, Inc. 66. Ribosomes: Protein Factories Ribosomes are complexes made of ribosomalRNA and protein Ribosomes carry out protein synthesis in twolocations In the cytosol (free ribosomes) On the outside of the endoplasmic reticulum or thenuclear envelope (bound ribosomes) 2014 Pearson Education, Inc. 67. Figure 6.10RibosomesER 2014 Pearson Education, Inc.TEM showing ERand ribosomesFree ribosomes in cytosolEndoplasmicreticulum (ER)Ribosomes bound to ERLargesubunitSmallsubunitDiagram of aribosomeComputer modelof a ribosome0.25 m 68. Figure 6.10aTEM showing ERand ribosomes 2014 Pearson Education, Inc.Free ribosomes in cytosolEndoplasmicreticulum (ER)Ribosomes bound to ERLargesubunitSmallsubunitDiagram of aribosome0.25 m 69. Figure 6.10b 2014 Pearson Education, Inc.TEM showing ERand ribosomesFree ribosomesin cytosolEndoplasmicreticulum (ER)Ribosomesbound to ER0.25 m 70. Figure 6.10c 2014 Pearson Education, Inc.LargesubunitSmallsubunitComputer modelof a ribosome 71. Concept 6.4: The endomembrane systemregulates protein traffic and performs metabolicfunctions in the cell The endomembrane system consists of Nuclear envelope Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Plasma membrane These components are either continuous orconnected via transfer by vesicles 2014 Pearson Education, Inc. 72. The Endoplasmic Reticulum: BiosyntheticFactory The endoplasmic reticulum (ER) accounts formore than half of the total membrane in manyeukaryotic cells The ER membrane is continuous with the nuclearenvelope There are two distinct regions of ER Smooth ER, which lacks ribosomes Rough ER, whose surface is studded withribosomes 2014 Pearson Education, Inc. 73. Figure 6.11Smooth ERRough ER Nuclear 2014 Pearson Education, Inc.envelopeER lumenCisternaeRibosomesTransport vesicleTransitionalERSmooth ER Rough ER0.20 m 74. Figure 6.11aSmooth ER Rough ER 2014 Pearson Education, Inc.0.20 m 75. Video: ER and Mitochondria in Leaf Cells 2014 Pearson Education, Inc. 76. Video: Staining of Endoplasmic Reticulum 2014 Pearson Education, Inc. 77. Functions of Smooth ER The smooth ER Synthesizes lipids Metabolizes carbohydrates Detoxifies drugs and poisons Stores calcium ions 2014 Pearson Education, Inc. 78. Functions of Rough ER The rough ER Has bound ribosomes, which secreteglycoproteins (proteins covalently bonded tocarbohydrates) Distributes transport vesicles, secretory proteinssurrounded by membranes Is a membrane factory for the cell 2014 Pearson Education, Inc. 79. The Golgi Apparatus: Shipping andReceiving Center The Golgi apparatus consists of flattenedmembranous sacs called cisternae Functions of the Golgi apparatus Modifies products of the ER Manufactures certain macromolecules Sorts and packages materials into transportvesicles 2014 Pearson Education, Inc. 80. Figure 6.12 2014 Pearson Education, Inc.0.1 mTEM of Golgi apparatusCisternaeGolgiapparatuscis face(receiving side ofGolgi apparatus)trans face(shipping side ofGolgi apparatus) 81. Figure 6.12a 2014 Pearson Education, Inc.0.1 mTEM of Golgi apparatus 82. Video: Golgi Complex in 3-D 2014 Pearson Education, Inc. 83. Lysosomes: Digestive Compartments A lysosome is a membranous sac of hydrolyticenzymes that can digest macromolecules Lysosomal enzymes work best in the acidicenvironment inside the lysosome Hydrolytic enzymes and lysosomal membranesare made by rough ER and then transferred to theGolgi apparatus for further processing 2014 Pearson Education, Inc. 84. Some types of cell can engulf another cell byphagocytosis; this forms a food vacuole A lysosome fuses with the food vacuole anddigests the molecules Lysosomes also use enzymes to recycle thecells own organelles and macromolecules,a process called autophagy 2014 Pearson Education, Inc. 85. Figure 6.13LysosomeFoodvacuoleLysosomeDigestiveenzymesPlasmamembrane 2014 Pearson Education, Inc.1 m(a)NucleusVesicle containingtwo damagedorganellesMitochondrionfragmentPeroxisomefragmentLysosomePeroxisomeMitochondrionVesicleDigestionAutophagy: lysosome breaking downdamaged organelles(b)DigestionPhagocytosis: lysosome digesting food1 m 86. Figure 6.13a 2014 Pearson Education, Inc.1 mLysosomeDigestiveenzymesPlasmamembrane(a)NucleusDigestionLysosomeFoodvacuolePhagocytosis: lysosome digesting food 87. Figure 6.13aa 2014 Pearson Education, Inc.Nucleus 1 mLysosome 88. Figure 6.13b 2014 Pearson Education, Inc.MitochondrionfragmentPeroxisomefragmentVesicle containingtwo damagedorganellesLysosomePeroxisomeMitochondrion DigestionVesicleAutophagy: lysosome breaking downdamaged organelles(b)1 m 89. Figure 6.13baMitochondrionfragmentPeroxisomefragment 2014 Pearson Education, Inc.Vesicle containingtwo damagedorganelles1 m 90. Animation: Lysosome Formation 2014 Pearson Education, Inc. 91. Video: Phagocytosis in Action 2014 Pearson Education, Inc. 92. Vacuoles: Diverse Maintenance Compartments Vacuoles are large vesicles derived from the ERand Golgi apparatus Vacuoles perform a variety of functions in differentkinds of cells 2014 Pearson Education, Inc. 93. Food vacuoles are formed by phagocytosis Contractile vacuoles, found in many freshwaterprotists, pump excess water out of cells Central vacuoles, found in many mature plantcells, hold organic compounds and water 2014 Pearson Education, Inc. 94. Figure 6.14 2014 Pearson Education, Inc.5 mCentral vacuoleNucleusCell wallChloroplastCytosolCentralvacuole 95. Figure 6.14a 2014 Pearson Education, Inc.5 mNucleusCell wallChloroplastCytosolCentralvacuole 96. Video: Paramecium Vacuole 2014 Pearson Education, Inc. 97. The Endomembrane System: A Review The endomembrane system is a complex anddynamic player in the cells compartmentalorganization 2014 Pearson Education, Inc. 98. Figure 6.15Smooth ER 2014 Pearson Education, Inc.NucleusRough ERcis Golgitrans GolgiPlasmamembrane 99. Video: ER to Golgi Traffic 2014 Pearson Education, Inc. 100. Video: Secretion from the Golgi 2014 Pearson Education, Inc. 101. Concept 6.5: Mitochondria and chloroplastschange energy from one form to another Mitochondria are the sites of cellular respiration,a metabolic process that uses oxygen togenerate ATP Chloroplasts, found in plants and algae, are thesites of photosynthesis Peroxisomes are oxidative organelles 2014 Pearson Education, Inc. 102. The Evolutionary Origins of Mitochondria andChloroplasts Mitochondria and chloroplasts have similaritieswith bacteria Enveloped by a double membrane Contain free ribosomes and circular DNA molecules Grow and reproduce somewhat independentlyin cells These similarities led to the endosymbionttheory 2014 Pearson Education, Inc. 103. The endosymbiont theory suggests that an earlyancestor of eukaryotes engulfed an oxygen-usingnonphotosynthetic prokaryotic cell The engulfed cell formed a relationship with thehost cell, becoming an endosymbiont The endosymbionts evolved into mitochondria At least one of these cells may have then taken upa photosynthetic prokaryote, which evolved into achloroplast 2014 Pearson Education, Inc. 104. Figure 6.16Endoplasmicreticulum 2014 Pearson Education, Inc.NucleusNuclearenvelopeAncestor ofeukaryotic cells (host cell)Engulfing of oxygen-usingnonphotosyntheticprokaryote, whichbecomes a mitochondrionNonphotosyntheticeukaryoteEngulfing ofphotosyntheticprokaryoteMitochondrionMitochondrionChloroplastAt leastone cellPhotosynthetic eukaryote 105. Mitochondria: Chemical Energy Conversion Mitochondria are in nearly all eukaryotic cells They have a smooth outer membrane and aninner membrane folded into cristae The inner membrane creates two compartments:intermembrane space and mitochondrial matrix Some metabolic steps of cellular respiration arecatalyzed in the mitochondrial matrix Cristae present a large surface area for enzymesthat synthesize ATP 2014 Pearson Education, Inc. 106. Figure 6.17Mitochondrion 2014 Pearson Education, Inc.IntermembranespaceOutermembraneDNAInnermembraneFreeribosomesin themitochondrialmatrixCristaeMatrix(a) Diagram and TEM of mitochondrion0.1 m10 mMitochondriaMitochondrialDNANuclear DNANetwork of mitochondria inEuglena (LM)(b) 107. Figure 6.17aMitochondrion 2014 Pearson Education, Inc.IntermembranespaceOutermembraneDNAInnermembraneFreeribosomesin themitochondrialmatrixCristaeMatrixDiagram and TEM of mitochondrion0.1 m(a) 108. Figure 6.17aa 2014 Pearson Education, Inc.OutermembraneInnermembraneCristaeMatrix0.1 m 109. Figure 6.17b 2014 Pearson Education, Inc.MitochondriaMitochondrialDNANuclear DNA(b) Network of mitochondria inEuglena (LM)10 m 110. Video: Mitochondria in 3-D 2014 Pearson Education, Inc. 111. Chloroplasts: Capture of Light Energy Chloroplasts contain the green pigmentchlorophyll, as well as enzymes and othermolecules that function in photosynthesis Chloroplasts are found in leaves and other greenorgans of plants and in algae 2014 Pearson Education, Inc. 112. Figure 6.18Chloroplast 2014 Pearson Education, Inc.Ribosomes StromaInnerand outermembranesGranumDNAThylakoid Intermembrane spaceDiagram (a) and TEM of chloroplast (b)Chloroplasts in analgal cell1 m50 mChloroplasts(red) 113. Figure 6.18a 2014 Pearson Education, Inc.Ribosomes StromaInnerand outermembranesGranumDNAThylakoid Intermembrane space(a) Diagram and TEM of chloroplast1 m 114. Figure 6.18aa 2014 Pearson Education, Inc.StromaInnerand outermembranesGranum1 m 115. Figure 6.18b 2014 Pearson Education, Inc.(b) Chloroplasts in analgal cell50 mChloroplasts(red) 116. Chloroplast structure includes Thylakoids, membranous sacs, stacked to form agranum Stroma, the internal fluid The chloroplast is one of a group of plantorganelles, called plastids 2014 Pearson Education, Inc. 117. Peroxisomes: Oxidation Peroxisomes are specialized metaboliccompartments bounded by a single membrane Peroxisomes produce hydrogen peroxide andconvert it to water Peroxisomes perform reactions with manydifferent functions How peroxisomes are related to other organellesis still unknown 2014 Pearson Education, Inc. 118. Figure 6.19Chloroplasts 2014 Pearson Education, Inc.PeroxisomeMitochon-drion1 m 119. Concept 6.6: The cytoskeleton is a network offibers that organizes structures and activities inthe cell The cytoskeleton is a network of fibers extendingthroughout the cytoplasm It organizes the cells structures and activities,anchoring many organelles It is composed of three types of molecularstructures Microtubules Microfilaments Intermediate filaments 2014 Pearson Education, Inc. 120. Figure 6.20 2014 Pearson Education, Inc.10 m 121. Video: The Cytoskeleton in Neuron GrowthCone 2014 Pearson Education, Inc. 122. Video: Interphase Microtubule Dynamics 2014 Pearson Education, Inc. 123. Video: Microtubule Dynamics 2014 Pearson Education, Inc. 124. Video: Actin Visualization in Dendrites 2014 Pearson Education, Inc. 125. Video: Cytoskeletal Protein Dynamics 2014 Pearson Education, Inc. 126. Roles of the Cytoskeleton: Support and Motility The cytoskeleton helps to support the cell andmaintain its shape It interacts with motor proteins to produce motility Inside the cell, vesicles can travel along tracksprovided by the cytoskeleton 2014 Pearson Education, Inc. 127. Figure 6.21Motor protein(ATP powered)Microtubuleof cytoskeleton(a)Motor proteins walk vesicles along cytoskeletal 2014 Pearson Education, Inc.0.25 mfibers.Microtubule Vesicles(b) SEM of a squid giant axonReceptor formotor proteinVesicleATP 128. Figure 6.21aMicrotubule Vesicles 0.25 m(b) SEM of a squid giant axon 2014 Pearson Education, Inc. 129. Video: Movement of Organelles In Vitro 2014 Pearson Education, Inc. 130. Video: Movement of Organelles In Vivo 2014 Pearson Education, Inc. 131. Video: Transport Along Microtubules 2014 Pearson Education, Inc. 132. Components of the Cytoskeleton Three main types of fibers make up thecytoskeleton Microtubules are the thickest of the threecomponents of the cytoskeleton Microfilaments, also called actin filaments, are thethinnest components Intermediate filaments are fibers with diameters in amiddle range 2014 Pearson Education, Inc. 133. Table 6.1 2014 Pearson Education, Inc. 134. Table 6.1a 2014 Pearson Education, Inc. 135. Table 6.1b 2014 Pearson Education, Inc. 136. Table 6.1ba 2014 Pearson Education, Inc. 137. Table 6.1c 2014 Pearson Education, Inc. 138. Table 6.1ca 2014 Pearson Education, Inc. 139. Table 6.1d 2014 Pearson Education, Inc. 140. Table 6.1da 2014 Pearson Education, Inc. 141. Microtubules Microtubules are hollow rods about 25 nm indiameter and about 200 nm to 25 microns long Functions of microtubules Shaping the cell Guiding movement of organelles Separating chromosomes during cell division 2014 Pearson Education, Inc. 142. Centrosomes and Centrioles In animal cells, microtubules grow out from acentrosome near the nucleus In animal cells, the centrosome has a pair ofcentrioles, each with nine triplets of microtubulesarranged in a ring 2014 Pearson Education, Inc. 143. Figure 6.22 2014 Pearson Education, Inc.Microtubule0.25 mCentrosomeCentriolesLongitudinalsection of onecentriole MicrotubulesCross sectionof the other centriole 144. Figure 6.22a 2014 Pearson Education, Inc.0.25 mLongitudinalsection of onecentriole MicrotubulesCross sectionof the other centriole 145. Cilia and Flagella Microtubules control the beating of flagella andcilia, microtubule-containing extensions thatproject from some cells Cilia and flagella differ in their beating patterns 2014 Pearson Education, Inc. 146. Figure 6.23 2014 Pearson Education, Inc.5 m15 m(a)(b)Motion of flagellaDirection of swimmingMotion of ciliaDirection of organisms movementPowerstrokeRecoverystroke 147. Figure 6.23a 2014 Pearson Education, Inc.5 m 148. Video: Chlamydomonas 2014 Pearson Education, Inc. 149. Video: Flagellum Movement in SwimmingSperm 2014 Pearson Education, Inc. 150. Video: Motion of Isolated Flagellum 2014 Pearson Education, Inc. 151. Video: Paramecium Cilia 2014 Pearson Education, Inc. 152. Figure 6.23b 2014 Pearson Education, Inc.15 m 153. Video: Ciliary Motion 2014 Pearson Education, Inc. 154. Cilia and flagella share a common structure A core of microtubules sheathed by theplasma membrane A basal body that anchors the cilium or flagellum A motor protein called dynein, which drives thebending movements of a cilium or flagellum 2014 Pearson Education, Inc. 155. Figure 6.24 2014 Pearson Education, Inc.0.1 m0.5 mCross section ofmotile cilium0.1 mMicrotubulesPlasmamembraneBasalbodyLongitudinal sectionof motile cilium(a)Triplet(b)Outer microtubuledoubletMotor proteins(dyneins)CentralmicrotubuleRadial spokeCross-linkingproteins betweenouter doubletsPlasmamembrane(c) Cross section of basal body 156. Figure 6.24a 2014 Pearson Education, Inc.0.5 mMicrotubulesPlasmamembraneBasalbodyLongitudinal sectionof motile cilium(a) 157. Figure 6.24b0.1 m 2014 Pearson Education, Inc.Outer microtubuledoubletMotor proteins(dyneins)CentralmicrotubuleRadial spokeCross-linkingproteins betweenouter doubletsPlasmamembraneCross section ofmotile cilium(b) 158. Figure 6.24ba 2014 Pearson Education, Inc.Outer microtubuledoubletMotor proteins(dyneins)CentralmicrotubuleRadial spokeCross-linkingproteins between0.1 mCross section of outer doubletsmotile cilium(b) 159. Figure 6.24c 2014 Pearson Education, Inc.0.1 mTriplet(c) Cross section of basal body 160. Figure 6.24ca 2014 Pearson Education, Inc.0.1 mTriplet(c) Cross section of basal body 161. Animation: Cilia and Flagella 2014 Pearson Education, Inc. 162. Video: Microtubule Sliding in FlagellumMovement 2014 Pearson Education, Inc. 163. How dynein walking moves flagella and cilia Dynein arms alternately grab, move, and releasethe outer microtubules Protein cross-links limit sliding Forces exerted by dynein arms cause doubletsto curve, bending the cilium or flagellum 2014 Pearson Education, Inc. 164. Microfilaments (Actin Filaments) Microfilaments are solid rods about 7 nm indiameter, built as a twisted double chain ofactin subunits The structural role of microfilaments is to beartension, resisting pulling forces within the cell They form a 3-D network called the cortex justinside the plasma membrane to help support thecells shape Bundles of microfilaments make up the core ofmicrovilli of intestinal cells 2014 Pearson Education, Inc. 165. Figure 6.25 2014 Pearson Education, Inc.MicrovillusPlasma membraneMicrofilaments (actinfilaments)Intermediate filaments0.25 m 166. Microfilaments that function in cellular motilitycontain the protein myosin in addition to actin In muscle cells, thousands of actin filaments arearranged parallel to one another Thicker filaments composed of myosin interdigitatewith the thinner actin fibers 2014 Pearson Education, Inc. 167. Figure 6.26Muscle cell 2014 Pearson Education, Inc.0.5 mActinfilamentMyosinfilamentMyosinhead Chloroplast(a)(b)Myosin motors in muscle cell contraction (c) Cytoplasmic streaming inplant cellsAmoeboid movementExtendingpseudopodiumCortex (outer cytoplasm):gel with actin networkInner cytoplasm(more fluid)100 m30 m 168. Figure 6.26aMuscle cell 2014 Pearson Education, Inc.0.5 mActinfilamentMyosinfilamentMyosinhead(a) Myosin motors in muscle cell contraction 169. Figure 6.26aa 2014 Pearson Education, Inc.0.5 m 170. Figure 6.26b(b) Amoeboid movement 2014 Pearson Education, Inc.ExtendingpseudopodiumCortex (outer cytoplasm):gel with actin networkInner cytoplasm(more fluid)100 m 171. Video: Actin Network in Crawling Cells 2014 Pearson Education, Inc. 172. Figure 6.26c 2014 Pearson Education, Inc.Chloroplast(c) Cytoplasmic streaming inplant cells30 m 173. Video: Cytoplasmic Streaming 2014 Pearson Education, Inc. 174. Video: Chloroplast Movement 2014 Pearson Education, Inc. 175. Localized contraction brought about by actin andmyosin also drives amoeboid movement Cells crawl along a surface by extendingpseudopodia (cellular extensions) and movingtoward them 2014 Pearson Education, Inc. 176. Cytoplasmic streaming is a circular flow ofcytoplasm within cells This streaming speeds distribution of materialswithin the cell In plant cells, actin-myosin interactions and sol-geltransformations drive cytoplasmic streaming 2014 Pearson Education, Inc. 177. Intermediate Filaments Intermediate filaments range in diameter from812 nanometers, larger than microfilamentsbut smaller than microtubules They support cell shape and fix organellesin place Intermediate filaments are more permanentcytoskeleton fixtures than the other two classes 2014 Pearson Education, Inc. 178. Concept 6.7: Extracellular components andconnections between cells help coordinatecellular activities Most cells synthesize and secrete materials thatare external to the plasma membrane These extracellular structures are involved in agreat many cellular functions 2014 Pearson Education, Inc. 179. Cell Walls of Plants The cell wall is an extracellular structure thatdistinguishes plant cells from animal cells Prokaryotes, fungi, and some unicellulareukaryotes also have cell walls The cell wall protects the plant cell, maintains itsshape, and prevents excessive uptake of water Plant cell walls are made of cellulose fibersembedded in other polysaccharides and protein 2014 Pearson Education, Inc. 180. Plant cell walls may have multiple layers Primary cell wall: Relatively thin and flexible Middle lamella: Thin layer between primary wallsof adjacent cells Secondary cell wall (in some cells): Addedbetween the plasma membrane and the primarycell wall Plasmodesmata are channels between adjacentplant cells 2014 Pearson Education, Inc. 181. Figure 6.27 2014 Pearson Education, Inc.Secondarycell wallPrimarycell wallMiddlelamellaCentral vacuoleCytosolPlasma membranePlant cell wallsPlasmodesmata1 m 182. Figure 6.27a 2014 Pearson Education, Inc.Secondarycell wallPrimarycell wallMiddlelamella1 m 183. The Extracellular Matrix (ECM) of Animal Cells Animal cells lack cell walls but are covered by anelaborate extracellular matrix (ECM) The ECM is made up of glycoproteins such ascollagen, proteoglycans, and fibronectin ECM proteins bind to receptor proteins in theplasma membrane called integrins 2014 Pearson Education, Inc. 184. Figure 6.28CollagenFibronectinPlasmamembrane 2014 Pearson Education, Inc.A proteoglycancomplexPolysaccharidemoleculeMicrofilamentsCarbo-hydratesCoreproteinProteoglycanmoleculeCYTOPLASMIntegrinsEXTRACELLULAR FLUID 185. Figure 6.28aCollagenFibronectinPlasmamembrane 2014 Pearson Education, Inc.A proteoglycancomplexMicrofilamentsCYTOPLASMIntegrinsEXTRACELLULAR FLUID 186. Figure 6.28b 2014 Pearson Education, Inc.PolysaccharidemoleculeCarbo-hydratesCoreproteinProteoglycanmolecule 187. Video: Cartoon Model of a Collagen Triple Helix 2014 Pearson Education, Inc. 188. Video: E-Cadherin Expression 2014 Pearson Education, Inc. 189. Video: Fibronectin Fibrils 2014 Pearson Education, Inc. 190. Video: Staining of the Cell-Cell Junctions 2014 Pearson Education, Inc. 191. The ECM has an influential role in the lives of cells ECM can regulate a cells behavior bycommunicating with a cell through integrins The ECM around a cell can influence the activityof gene in the nucleus Mechanical signaling may occur throughcytoskeletal changes, that trigger chemical signalsin the cell 2014 Pearson Education, Inc. 192. Cell Junctions Neighboring cells in tissues, organs, or organsystems often adhere, interact, and communicatethrough direct physical contact 2014 Pearson Education, Inc. 193. Plasmodesmata in Plant Cells Plasmodesmata are channels that perforate plantcell walls Through plasmodesmata, water and small solutes(and sometimes proteins and RNA) can pass fromcell to cell 2014 Pearson Education, Inc. 194. Figure 6.29Interiorof cellInteriorof cell 2014 Pearson Education, Inc.Cell walls0.5 m Plasmodesmata Plasma membranes 195. Tight Junctions, Desmosomes, and GapJunctions in Animal Cells Three types of cell junctions are common inepithelial tissues At tight junctions, membranes of neighboring cellsare pressed together, preventing leakage ofextracellular fluid Desmosomes (anchoring junctions) fasten cellstogether into strong sheets Gap junctions (communicating junctions) providecytoplasmic channels between adjacent cells 2014 Pearson Education, Inc. 196. Figure 6.30 2014 Pearson Education, Inc.Tight junctions preventfluid from movingacross a layer of cells.TightjunctionTEM0.5 mTight junctionIntermediatefilamentsDesmosomeGapjunctionIons or smallmoleculesPlasmamembranes ofadjacent cellsSpacebetween cellsExtracellularmatrixDesmosome(TEM)1 m0.1 mTEMGap junctions 197. Figure 6.30aTight junctionsprevent fluidfrom movingacross a layerof cells.Spacebetween cells 2014 Pearson Education, Inc.Tight junctionIntermediatefilamentsDesmosomeGapjunctionIons or smallmoleculesPlasmamembranes ofadjacent cellsExtracellularmatrix 198. Figure 6.30b 2014 Pearson Education, Inc.TightjunctionTEM0.5 m 199. Figure 6.30c 2014 Pearson Education, Inc.1 mDesmosome(TEM) 200. Figure 6.30d 2014 Pearson Education, Inc.0.1 mTEMGap junctions 201. Animation: Desmosomes 2014 Pearson Education, Inc. 202. Animation: Gap Junctions 2014 Pearson Education, Inc. 203. Animation: Tight Junctions 2014 Pearson Education, Inc. 204. The Cell: A Living Unit Greater Than the Sum ofIts Parts Cells rely on the integration of structures andorganelles in order to function For example, a macrophages ability to destroybacteria involves the whole cell, coordinatingcomponents such as the cytoskeleton, lysosomes,and plasma membrane 2014 Pearson Education, Inc. 205. Figure 6.315 m 2014 Pearson Education, Inc. 206. Figure 6.UN01a 2014 Pearson Education, Inc.1 mBuddingcellMature parentcell 207. Figure 6.UN01b 2014 Pearson Education, Inc.V =43_ r 3r d 208. Figure 6.UN02 2014 Pearson Education, Inc.Nucleus5 m 209. Figure 6.UN03 2014 Pearson Education, Inc. 210. Figure 6.UN04 2014 Pearson Education, Inc. 211. Figure 6.UN05 2014 Pearson Education, Inc. 212. Figure 6.UN06 2014 Pearson Education, Inc.Epithelial cell