A Tour of the CellA Tour of the Cell
Ch. 6Ch. 6
Sections 6.1, 6.2Sections 6.1, 6.2
3 Objectives in the Section3 Objectives in the Section
1.1. Microscope types – what kindMicroscope types – what kind
is be...
MicroscopesMicroscopes
how we view cellshow we view cells
Early MicroscopesEarly Microscopes
 First microscopeFirst microscope
 Jansen (Dutch) -Jansen (Dutch) -
15951595
 Christ...
Leeuwenhoek’sLeeuwenhoek’s MicroscopesMicroscopes
 Brightest, clearest lensesBrightest, clearest lenses
 Single lens,Sin...
 500500 timestimes
better thanbetter than
human eyehuman eye
LightLight
MicroscopeMicroscope
Light MicroscopesLight Microscopes
 Early scopes and modern scopes are lightEarly scopes and modern scopes are light
micr...
MagnificationMagnification
 The ratio of the projected image to the realThe ratio of the projected image to the real
size...
Sizes of cellsSizes of cells
 OneOne MICROMETERMICROMETER = 1/ 1,000,000 m= 1/ 1,000,000 m
 OneOne NANOMETERNANOMETER = ...
ResolutionResolution
 A measure of how clear an image isA measure of how clear an image is
 Determined by the minimum di...
ResolutionResolution
 Human eye's resolving powerHuman eye's resolving power
 Ability to distinguish betweenAbility to d...
 Reverses image under field of viewReverses image under field of view
Light MicroscopeLight Microscope
Dark-Field MicroscopesDark-Field Microscopes
 Light comes from the sideLight comes from the side,, makesmakes hugehuge
sh...
Phase-contrast MicroscopePhase-contrast Microscope
 Waves of lightWaves of light
are set up,are set up,
bounced offbounce...
Electron MicroscopesElectron Microscopes
 Developed in theDeveloped in the
1950s1950s
 Instead of light, aInstead of lig...
Transmission Electron MicroscopeTransmission Electron Microscope
(T.E.M.)(T.E.M.)
 Aims aAims a beam of electronsbeam of ...
T.E.M. X-secT.E.M. X-sec
Golgi
Actin Filament
Mitochondrion
Preparation of specimenPreparation of specimen
 Since cells are mostly water,Since cells are mostly water, need dye tonee...
Scanning Electron MicroscopeScanning Electron Microscope
(S.E.M.)(S.E.M.)
 Works like sonar, usingWorks like sonar, using...
S.E.M.S.E.M.
Pollen grains
Ant
Red and
white
blood
cells
Preparation of specimensPreparation of specimens
 First embedded in waxFirst embedded in wax
 Sliced with aSliced with a...
Pros & Cons of Microscope TypesPros & Cons of Microscope Types
LightLight ScanningScanning
ElectronElectron
TransmissionTr...
Quick ThinkQuick Think
 With your neighbor, DISCUSS:With your neighbor, DISCUSS:
 What type of microscope wouldWhat type...
Separation of Organelles bySeparation of Organelles by CellCell
FractionationFractionation
 Using a centrifuge to separat...
Prokaryotic Cells vs.Prokaryotic Cells vs.
Eukaryotic CellsEukaryotic Cells
PROKARYOTESPROKARYOTES
TheyThey are:are:
BacteriaBacteria
 Have plasma membraneHave plasma membrane (aka cell membrane)(aka cell membrane)
++ cell wallcell wall
 NoNo membrane-bo...
EUKARYOTESEUKARYOTES
 Much moreMuch more complexcomplex
 Contain MANYContain MANY membrane-boundmembrane-bound organelle...
Cell SizeCell Size
InIn eukaryoteseukaryotes – cells– cells
varyvary greatly,greatly, butbut
basically allbasically all s...
Critical Question:Critical Question:
Why Do Cells Need to BeWhy Do Cells Need to Be
ExtremelyExtremely Small?Small?
Answer:Answer:
 Surface to volume ratioSurface to volume ratio needs to be largeneeds to be large
 LOTS of materialsLOTS...
Diffusion of substances across theDiffusion of substances across the
plasma membraneplasma membrane
 Only so much stuff c...
Increase Surface/Volume RatioIncrease Surface/Volume Ratio
Cell ShapeCell Shape
Tend to beTend to be sphericalspherical
because of cohesion &because of cohesion &
surface tensionsu...
OrganellesOrganelles
 Eukaryotic cells haveEukaryotic cells have
elaborateelaborate internalinternal
membranesmembranes t...
Cell ComponentsCell Components
Animal CellAnimal Cell
Plant CellPlant Cell
The Cell Parts ProjectThe Cell Parts Project
 NucleusNucleus
 NucleolusNucleolus
 RibosomesRibosomes
 Smooth ERSmooth ...
Groups and TopicsGroups and Topics
You can choose your partner,You can choose your partner,
but topics will be assigned o...
AP BIO CH. 6.1-6.2
AP BIO CH. 6.1-6.2
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  • http://www.olympusmicro.com/primer/anatomy/introduction.html Great site with lots of pics and scope info
  • Point out that prokaryotes ARE organized and complex; especially biochemically; accounts for their incredible diversity
  • Use box of tissues example here: Box itself has certain SA to volume ratio – tissues inside take up same volume, but much greater SA
  • AP BIO CH. 6.1-6.2

    1. 1. A Tour of the CellA Tour of the Cell Ch. 6Ch. 6 Sections 6.1, 6.2Sections 6.1, 6.2
    2. 2. 3 Objectives in the Section3 Objectives in the Section 1.1. Microscope types – what kindMicroscope types – what kind is best for different jobsis best for different jobs 2.2. Differences betweenDifferences between prokaryotes and eukaryotesprokaryotes and eukaryotes 3.3. Why cells need to be smallWhy cells need to be small
    3. 3. MicroscopesMicroscopes how we view cellshow we view cells
    4. 4. Early MicroscopesEarly Microscopes  First microscopeFirst microscope  Jansen (Dutch) -Jansen (Dutch) - 15951595  Christopher Cock’sChristopher Cock’s compound scopescompound scopes (1665) used by(1665) used by RobertRobert HookHook, Father of cell, Father of cell biologybiology
    5. 5. Leeuwenhoek’sLeeuwenhoek’s MicroscopesMicroscopes  Brightest, clearest lensesBrightest, clearest lenses  Single lens,Single lens, magnified overmagnified over 200x200x  Impressive observerImpressive observer of protistsof protists
    6. 6.  500500 timestimes better thanbetter than human eyehuman eye LightLight MicroscopeMicroscope
    7. 7. Light MicroscopesLight Microscopes  Early scopes and modern scopes are lightEarly scopes and modern scopes are light microscopes (LMs)microscopes (LMs) Visible light passes through the specimenVisible light passes through the specimen Image magnified by a series of lensesImage magnified by a series of lenses
    8. 8. MagnificationMagnification  The ratio of the projected image to the realThe ratio of the projected image to the real size of the objectsize of the object  LMs can effectively magnify to ~ 1000xLMs can effectively magnify to ~ 1000x
    9. 9. Sizes of cellsSizes of cells  OneOne MICROMETERMICROMETER = 1/ 1,000,000 m= 1/ 1,000,000 m  OneOne NANOMETERNANOMETER = 1/1,000,000,000 m= 1/1,000,000,000 m
    10. 10. ResolutionResolution  A measure of how clear an image isA measure of how clear an image is  Determined by the minimum distance atDetermined by the minimum distance at which 2 points can still be distinguished aswhich 2 points can still be distinguished as 2 separate points2 separate points  LMs have resolution of ~0.2 micrometersLMs have resolution of ~0.2 micrometers at bestat best Poor resolution At what point can you no longer distinguish these as separate lines?
    11. 11. ResolutionResolution  Human eye's resolving powerHuman eye's resolving power  Ability to distinguish betweenAbility to distinguish between lines =lines = 1/10 mm1/10 mm  If closer, lines merge into 1 lineIf closer, lines merge into 1 line
    12. 12.  Reverses image under field of viewReverses image under field of view Light MicroscopeLight Microscope
    13. 13. Dark-Field MicroscopesDark-Field Microscopes  Light comes from the sideLight comes from the side,, makesmakes hugehuge shadowsshadows and contrastsand contrasts Good for LIVING CELLS
    14. 14. Phase-contrast MicroscopePhase-contrast Microscope  Waves of lightWaves of light are set up,are set up, bounced offbounced off the specimenthe specimen  InterferenceInterference causedcaused byby shape of cells isshape of cells is plotted byplotted by
    15. 15. Electron MicroscopesElectron Microscopes  Developed in theDeveloped in the 1950s1950s  Instead of light, aInstead of light, a beam of electrons isbeam of electrons is focused on specimenfocused on specimen
    16. 16. Transmission Electron MicroscopeTransmission Electron Microscope (T.E.M.)(T.E.M.)  Aims aAims a beam of electronsbeam of electrons instead ofinstead of light waveslight waves THROUGHTHROUGH a section ofa section of thethe specimenspecimen  200,000200,000 times bettertimes better than the eyethan the eye
    17. 17. T.E.M. X-secT.E.M. X-sec Golgi Actin Filament Mitochondrion
    18. 18. Preparation of specimenPreparation of specimen  Since cells are mostly water,Since cells are mostly water, need dye toneed dye to show up,show up, block light raysblock light rays  Hydrophobic andHydrophobic and hydrophillichydrophillic stainsstains will dye organelleswill dye organelles different densitiesdifferent densities
    19. 19. Scanning Electron MicroscopeScanning Electron Microscope (S.E.M.)(S.E.M.)  Works like sonar, usingWorks like sonar, using electronselectrons toto bounce off specimen's surfacebounce off specimen's surface  Limited resolutionLimited resolution butbut greatgreat 3-D3-D effecteffect!!
    20. 20. S.E.M.S.E.M.
    21. 21. Pollen grains Ant Red and white blood cells
    22. 22. Preparation of specimensPreparation of specimens  First embedded in waxFirst embedded in wax  Sliced with aSliced with a MICROTOMEMICROTOME  Specimens "shadowed"Specimens "shadowed" with metalwith metal,, for reflection, contrastfor reflection, contrast  ALL THESEALL THESE PROCESSESPROCESSES KILLKILL CELLSCELLS
    23. 23. Pros & Cons of Microscope TypesPros & Cons of Microscope Types LightLight ScanningScanning ElectronElectron TransmissionTransmission ElectronElectron ProsPros Can studyCan study living cellsliving cells Gives details onGives details on surface of specimen;surface of specimen; resolution 0.002resolution 0.002 micrometersmicrometers Good for studyingGood for studying internal cellinternal cell structures; resolutionstructures; resolution 0.002 micrometers0.002 micrometers ConsCons MagnificationMagnification to only 1000x,to only 1000x, resolutionresolution only 0.2only 0.2 micrometermicrometer Preparation of cellsPreparation of cells kills them; limitedkills them; limited resolutionresolution Preparation of cellsPreparation of cells kills them; need verykills them; need very thin sections of cellthin sections of cell parts (no depth)parts (no depth)
    24. 24. Quick ThinkQuick Think  With your neighbor, DISCUSS:With your neighbor, DISCUSS:  What type of microscope wouldWhat type of microscope would you use to studyyou use to study 1.1. A living white blood cell?A living white blood cell? 2.2. The details of surface texture ofThe details of surface texture of hair?hair? 3.3. The detailed structure of anThe detailed structure of an organelle?organelle?
    25. 25. Separation of Organelles bySeparation of Organelles by CellCell FractionationFractionation  Using a centrifuge to separate out successivelyUsing a centrifuge to separate out successively smaller cell components for studysmaller cell components for study  Cell parts separated by size and densityCell parts separated by size and density
    26. 26. Prokaryotic Cells vs.Prokaryotic Cells vs. Eukaryotic CellsEukaryotic Cells
    27. 27. PROKARYOTESPROKARYOTES TheyThey are:are: BacteriaBacteria
    28. 28.  Have plasma membraneHave plasma membrane (aka cell membrane)(aka cell membrane) ++ cell wallcell wall  NoNo membrane-boundmembrane-bound organellesorganelles  NONO NUCLEAR MEMBRANE (NUCLEAR MEMBRANE (no nucleusno nucleus)) DNA in strands in mid-cellDNA in strands in mid-cell  Heterotrophic, phototrophic & chemotrophicHeterotrophic, phototrophic & chemotrophic formsforms ProkaryotesProkaryotes
    29. 29. EUKARYOTESEUKARYOTES  Much moreMuch more complexcomplex  Contain MANYContain MANY membrane-boundmembrane-bound organellesorganelles  DNADNA containedcontained in a nucleusin a nucleus membranemembrane  IncludesIncludes ALLALL animals,animals, plants, protists, &plants, protists, & fungifungi
    30. 30. Cell SizeCell Size InIn eukaryoteseukaryotes – cells– cells varyvary greatly,greatly, butbut basically allbasically all similar insimilar in structure & sizestructure & size 10 30 micrometers‑10 30 micrometers‑  Largest cell =Largest cell = eggseggs  Zygote divides rapidly toZygote divides rapidly to get new cells to correct sizeget new cells to correct size
    31. 31. Critical Question:Critical Question: Why Do Cells Need to BeWhy Do Cells Need to Be ExtremelyExtremely Small?Small?
    32. 32. Answer:Answer:  Surface to volume ratioSurface to volume ratio needs to be largeneeds to be large  LOTS of materialsLOTS of materials need to pass through plasmaneed to pass through plasma membranemembrane  DiffusionDiffusion only works well across very shortonly works well across very short distancesdistances  NucleusNucleus can only handle so much info at oncecan only handle so much info at once would “short out” if cells were much larger‑would “short out” if cells were much larger‑
    33. 33. Diffusion of substances across theDiffusion of substances across the plasma membraneplasma membrane  Only so much stuff can pass across theOnly so much stuff can pass across the membrane at any particular locationmembrane at any particular location  Larger cells cannot move enoughLarger cells cannot move enough materials in and out to support the cellmaterials in and out to support the cell
    34. 34. Increase Surface/Volume RatioIncrease Surface/Volume Ratio
    35. 35. Cell ShapeCell Shape Tend to beTend to be sphericalspherical because of cohesion &because of cohesion & surface tensionsurface tension  Strongest structuralStrongest structural shape, stableshape, stable (like bubbles(like bubbles & balloons)& balloons)  If NOT spherical,If NOT spherical, cell needscell needs internalinternal and/orand/or externalexternal
    36. 36. OrganellesOrganelles  Eukaryotic cells haveEukaryotic cells have elaborateelaborate internalinternal membranesmembranes that divide thethat divide the interior of the cell intointerior of the cell into compartmentscompartments  TheseThese membrane boundmembrane bound compartments are calledcompartments are called organellesorganelles  Each has a specific functionEach has a specific function  Each has a specific structureEach has a specific structure
    37. 37. Cell ComponentsCell Components Animal CellAnimal Cell
    38. 38. Plant CellPlant Cell
    39. 39. The Cell Parts ProjectThe Cell Parts Project  NucleusNucleus  NucleolusNucleolus  RibosomesRibosomes  Smooth ERSmooth ER  Rough ERRough ER  GolgiGolgi  Vacuoles (food,Vacuoles (food, contractile, central)contractile, central)  CentriolesCentrioles  MitochondriaMitochondria  ChloroplastChloroplast  CytoskeletonCytoskeleton  Cilia and flagellaCilia and flagella  Cell wallCell wall  LysosomesLysosomes  Plasma membranePlasma membrane Do not need details of p/s or c/r
    40. 40. Groups and TopicsGroups and Topics You can choose your partner,You can choose your partner, but topics will be assigned onbut topics will be assigned on a first come, first serveda first come, first served RANDOM basisRANDOM basis

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