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Chapter 6: A Tour of the Cell. The Beginning. First Living Cells - 1674. First Cells - 1665. Leeuwenhoek’s Microscope. Hooke’s Microscope. Studying Cells. Microscopes Light Electron Cell Fractionation. The Light Microscope. Light is transmitted through the specimen - PowerPoint PPT Presentation
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Chapter 6:Chapter 6:
A Tour of the CellA Tour of the Cell
The BeginningThe Beginning
Hooke’sHooke’s
MicroscopeMicroscope
First Cells - 1665First Cells - 1665
LeeuwenhoekLeeuwenhoek’s’s
MicroscopeMicroscope
First First Living Living Cells - 1674Cells - 1674
Studying CellsStudying Cells
• MicroscopesMicroscopes
• LightLight
• ElectronElectron
• Cell FractionationCell Fractionation
The Light MicroscopeThe Light Microscope
• Light is transmitted through the specimenLight is transmitted through the specimen
• Magnified and focused using lensesMagnified and focused using lenses
• Maximum magnification is around 1000XMaximum magnification is around 1000X
• Sample can be stained to see various Sample can be stained to see various organelles and internal structuresorganelles and internal structures
• Can look at preserved or living specimensCan look at preserved or living specimens
The Light MicroscopeThe Light Microscope• Light is transmitted through the Light is transmitted through the
specimenspecimen
• Magnified and focused using lensesMagnified and focused using lenses
• Maximum magnification is around Maximum magnification is around 1000X1000X
• Sample can be stained to see Sample can be stained to see various organelles and internal various organelles and internal structuresstructures
• Can view preserved or living Can view preserved or living specimensspecimens
Micrograph from Light MicroscopeMicrograph from Light Microscope
EuglenaEuglena, LM , LM 1000X1000X
ResolutionResolution
The Electron MicroscopeThe Electron Microscope
• Two types: Scanning (SEM) and Two types: Scanning (SEM) and Transmission (TEM)Transmission (TEM)
• Electrons are passed through the Electrons are passed through the specimen (TEM) or bounce off the specimen (TEM) or bounce off the surface (SEM)surface (SEM)
• Maximum magnification is around Maximum magnification is around 100,000X100,000X
• High resolutionHigh resolution
• All specimens MUST BE preserved – All specimens MUST BE preserved – no living cellsno living cells
Micrograph from Transmission Micrograph from Transmission Electron MicroscopeElectron Microscope
Figure 6.8bc
1 m
Cell wall
Vacuole
Nucleus
Mitochondrion
A single yeast cell(colorized TEM)
Micrograph from Scanning Micrograph from Scanning Electron MicroscopeElectron Microscope
Fig. 6-5
Cell FractionationCell Fractionation
• Technique used to separate Technique used to separate organelles and major structures organelles and major structures from one anotherfrom one another
• Involves centrifugationInvolves centrifugation
• Heavier components are pushed Heavier components are pushed to the bottom of the test tubeto the bottom of the test tube
• Can separate out using Can separate out using sequential centrifugations at sequential centrifugations at increasing speedsincreasing speeds
TECHNIQUE
Homogenization
Tissuecells
Homogenate
Centrifugation
Differentialcentrifugation
Centrifuged at1,000 g
(1,000 times theforce of gravity)
for 10 min Supernatantpoured intonext tube
20,000 g20 min
80,000 g60 min
Pellet rich innuclei andcellular debris
150,000 g3 hr
Pellet rich inmitochondria(and chloro-plasts if cellsare from a plant)
Pellet rich in“microsomes”(pieces of plasmamembranes andcells’ internalmembranes) Pellet rich in
ribosomes
Cell TheoryCell Theory
1.1. All organisms are made of All organisms are made of cellscells
2.2. All cells come from cellsAll cells come from cells
Features of All CellsFeatures of All Cells
1.1. Plasma membrane - selective barrier Plasma membrane - selective barrier
2.2. Cytoplasm – semifluid substance Cytoplasm – semifluid substance containing organelles and other containing organelles and other componentscomponents
3.3. DNA – genetic informationDNA – genetic information
4.4. Ribosomes – protein making structuresRibosomes – protein making structures
Prokaryotes vs. EukaryotesProkaryotes vs. Eukaryotes• DNA Location:DNA Location:
• Proks: nucleoid regionProks: nucleoid region
• Euks: nucleusEuks: nucleus
• OrganellesOrganelles
• Proks: no true organelles (no Proks: no true organelles (no internal membranes)internal membranes)
• Euks: membrane-bound Euks: membrane-bound organellesorganelles
• SizeSize
• Proks: smallerProks: smaller
• Euks: largerEuks: larger
Nucleoidregion
Prokaryotic cell
Nucleus
Co
lor i
z ed
TE
M 1
5, 0
00
Eukaryotic cellOrganelles
Fig. 6-8
Surface area increases whiletotal volume remains constant
5
11
6 150 750
125 1251
6 61.2
Total surface area
[Sum of the surface areas
(height width) of all
boxes
sides number of boxes]Total volume
[height width length number of boxes]
Surface-to-volume
(S-to-V) ratio
[surface area ÷ volume]
Does size matter?Does size matter?
Fig. 6-6
Fimbriae
Nucleoid
Ribosomes
Plasma membrane
Cell wall
Capsule
Flagella
Bacterialchromosome
(a) A typical rod-shaped bacterium
(b) A thin section through the bacterium Bacillus coagulans (TEM)
0.5 µm
Features of Prokaryotic CellsFeatures of Prokaryotic Cells
Organisms with eukaryotic cellsOrganisms with eukaryotic cells
1.1. AnimalsAnimals
2.2. PlantsPlants
3.3. FungiFungi
4.4. ProtistsProtists
Anim
al C
ell
Anim
al C
ell
Figure 6.8aENDOPLASMIC RETICULUM (ER)
RoughER
SmoothER
Nuclearenvelope
Nucleolus
Chromatin
Plasmamembrane
Ribosomes
Golgi apparatus
LysosomeMitochondrion
Peroxisome
Microvilli
MicrotubulesIntermediate filaments
Microfilaments
Centrosome
CYTOSKELETON:
Flagellum NUCLEUS
Pla
nt
Cell
Pla
nt
Cell
Figure 6.8c
NUCLEUS
Nuclearenvelope
Nucleolus
Chromatin
Golgiapparatus
Mitochondrion
Peroxisome
Plasma membrane
Cell wall
Wall of adjacent cell
Plasmodesmata
Chloroplast
Microtubules
Intermediatefilaments
Microfilaments
CYTOSKELETON
Central vacuole
Ribosomes
Smoothendoplasmicreticulum
Roughendoplasmic
reticulum
Features Found in Plant Cells, but Features Found in Plant Cells, but NOT Animal CellsNOT Animal Cells
1.1. Cell WallCell Wall
2.2. ChloroplastChloroplast
3.3. Central vacuoleCentral vacuole
4.4. PlasmodesmataPlasmodesmata
Features Found in Animal Cells, Features Found in Animal Cells, but NOT Plant Cellsbut NOT Plant Cells
1.1. LysosomesLysosomes
2.2. CentrosomesCentrosomes
3.3. FlagellaFlagella
Fig. 6-10
NucleolusNucleus
Rough ER
Nuclear lamina (TEM)
Close-up of nuclear envelope
1 µm
1 µm
0.25 µm
Ribosome
Pore complex
Nuclear pore
Outer membraneInner membraneNuclear envelope:
Chromatin
Surface ofnuclear envelope
Pore complexes (TEM)
Nucl
eus
Nucl
eus
Fig. 6-11
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large subunit
Small subunit
Diagram of a ribosomeTEM showing ER and ribosomes
0.5 µm
Rib
oso
me
Rib
oso
me
Transport vesiclefrom ER to GolgiRough ER
Nucleus
Smooth ER Nuclear envelope Golgi apparatus
Lysosome
Vacuole
Plasmamembrane
Transport vesicle fromGolgi to plasma membrane
Endomembrane System: Endomembrane System: OverviewOverview
Fig. 6-12Smooth ER
Rough ER Nuclear envelope
Transitional ER
Rough ERSmooth ERTransport vesicle
RibosomesCisternaeER lumen
200 nm
Endoplasmic Endoplasmic Reticulum Reticulum
(ER)(ER)
Smooth ERSmooth ER
Three functions of the Smooth Three functions of the Smooth ER:ER:
1.1. Lipid productionLipid production
2.2. Detoxifying enzymesDetoxifying enzymes
3.3. Calcium ion storageCalcium ion storage
Rough ERRough ER
Two functions of the Rough ER:Two functions of the Rough ER:
1.1. Membrane productionMembrane production
2.2. Along with ribosomes, produce proteins for Along with ribosomes, produce proteins for use within the endomembrane system or use within the endomembrane system or for secretion from the cellfor secretion from the cell
3.3. Protein modificationProtein modification
Transport vesiclebuds off
Ribosome
Polypeptide
Glycoprotein
Sugarchain
Rough ER
Secretary(glyco-) proteininside trans-port vesicle
Figure 6.12
cis face(“receiving” side ofGolgi apparatus)
trans face(“shipping” side ofGolgi apparatus)
0.1 m
TEM of Golgi apparatus
Cisternae
Golgi Apparatus (Golgi Complex)Golgi Apparatus (Golgi Complex)
Figure 6.13
Nucleus
Lysosome
1 m
Digestiveenzymes
Digestion
Food vacuole
LysosomePlasma membrane
(a) Phagocytosis
Vesicle containingtwo damagedorganelles
1 m
Mitochondrionfragment
Peroxisomefragment
(b) Autophagy
Peroxisome
VesicleMitochondrion
Lysosome
Digestion
LysosomeLysosome
Figure 6.14
Central vacuole
Cytosol
Nucleus
Cell wall
Chloroplast
Centralvacuole
5 m
Centr
al V
acu
ole
Centr
al V
acu
ole
Figure 6.15-1
Smooth ER
Nucleus
Rough ER
Plasmamembrane
Figure 6.15-2
Smooth ER
Nucleus
Rough ER
Plasmamembrane
cis Golgi
trans Golgi
Figure 6.15-3
Smooth ER
Nucleus
Rough ER
Plasmamembrane
cis Golgi
trans Golgi
Mitochondria: Powerhouse of the Mitochondria: Powerhouse of the CellCell
• Mitochondria are divided into two Mitochondria are divided into two compartments (separated by the compartments (separated by the innerinnermembrane):membrane):
1.1. InterIntermembrane spacemembrane space
2.2. Mitochondrial matrixMitochondrial matrix
Figure 6.16NucleusEndoplasmic
reticulum
Nuclear envelope
Ancestor ofeukaryotic cells(host cell)
Engulfing of oxygen-using nonphotosyntheticprokaryote, whichbecomes a mitochondrion
Mitochondrion
Nonphotosyntheticeukaryote
Mitochondrion
At leastone cell
Photosynthetic eukaryote
Engulfing ofphotosyntheticprokaryote
Chloroplast
Figure 6.17
Intermembrane space
Outermembrane
DNA
Innermembrane
Cristae
Matrix
Freeribosomesin themitochondrialmatrix
(a) Diagram and TEM of mitochondrion (b) Network of mitochondria in a protistcell (LM)
0.1 m
MitochondrialDNA
Nuclear DNA
Mitochondria
10 m
Mitochondria: Powerhouse of the Mitochondria: Powerhouse of the CellCell
Chloroplasts: Site of Chloroplasts: Site of PhotosynthesisPhotosynthesis
• Converts solar energy into chemical energyConverts solar energy into chemical energy
• Chloroplasts are divided into three Chloroplasts are divided into three compartments:compartments:
1.1. Intermembrane spaceIntermembrane space
2.2. StromaStroma
3.3. GranaGrana
Figure 6.18
RibosomesStroma
Inner and outermembranes
Granum
1 mIntermembrane spaceThylakoid
(a) Diagram and TEM of chloroplast (b) Chloroplasts in an algal cell
Chloroplasts(red)
50 m
DNA
Chloroplasts: Site of Chloroplasts: Site of PhotosynthesisPhotosynthesis
Figure 6.19
ChloroplastPeroxisome
Mitochondrion
1 m
PeroxisomePeroxisome
CytoskeletonCytoskeleton
• Microfilaments – Microfilaments – thinnestthinnest
• Intermediate Intermediate filamentsfilaments
• Microtubules – Microtubules – thickestthickest
Figure 6.20
10
m
CytoskeletonCytoskeleton
• Microfilaments – Microfilaments – thinnestthinnest
• Intermediate Intermediate filamentsfilaments
• Microtubules – Microtubules – thickestthickest
Table 6.1
Column of tubulin dimers
Tubulin dimer
25 nm
Actin subunit
7 nm
Keratin proteins
812 nm
Fibrous subunit (keratinscoiled together)
10 m 10 m 5 m
Figure 6.23
Direction of swimming
(b) Motion of cilia
Direction of organism’s movement
Power stroke Recovery stroke
(a) Motion of flagella5 m
15 m
Cili
a a
nd F
lagella
Cili
a a
nd F
lagella
Fig. 6-24
0.1 µm
Triplet
(c) Cross section of basal body
(a) Longitudinal section of cilium
0.5 µm
Plasma membrane
Basal body
Microtubules
(b) Cross section of cilium
Plasma membrane
Outer microtubule doublet
Dynein proteins
Central microtubuleRadial spoke
Protein cross-linking outer doublets
0.1 µm
Fig. 6-28
Secondary cell wall
Primary cell wall
Middle lamella
Central vacuoleCytosol
Plasma membrane
Plant cell walls
Plasmodesmata
1 µm
Fig. 6-30
EXTRACELLULAR FLUIDCollagen
Fibronectin
Plasmamembrane
Micro-filaments
CYTOPLASM
Integrins
Proteoglycancomplex
Polysaccharidemolecule
Carbo-hydrates
Coreprotein
Proteoglycanmolecule
Proteoglycan complex
Fig. 6-32
Tight junction
0.5 µm
1 µmDesmosome
Gap junction
Extracellularmatrix
0.1 µm
Plasma membranesof adjacent cells
Spacebetweencells
Gapjunctions
Desmosome
Intermediatefilaments
Tight junction
Tight junctions preventfluid from movingacross a layer of cells
Figure 6.UN01
Nucleus
(ER)
(Nuclearenvelope)