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Tour of the Cell
Today’s Topics
• Properties of all cells
• Prokaryotes and Eukaryotes
• Functions of Major Cellular
Organelles
– Information • Nucleus, Ribosomes – Synthesis&Transport
• ER, Golgi, Vesicles – Energy Conversion
• Mitochondria, Chloroplasts – Recycling
• Lysosome, Peroxisome – Structure and Movement • Cytoskeleton and Motor
Proteins • Cell Walls
9/16/11
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Common features of all cells
• Plasma Membrane
– defines inside from outside
• Cytosol
– Semifluid “inside” of the cell
• DNA “chromosomes”
- Genetic material – hereditary
instructions
• Ribosomes
– “factories” to synthesize proteins
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Bacterial (Prokaryotic) Cell
Ribosomes! Plasma membrane! Cell wall! Flagella! Bacterial chromosome! 0.5 !m!
No internal
membranes
5Contains internal organelles
Eukaryotic Cell
Figure 6.2b 1 mm 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm 0.1 nm Atoms Small molecules Lipids Proteins Ribosomes Viruses Smallest bacteria Mitochondrion Most bacteria Nucleus Most plant and animal cells Human egg L ig h t m ic ro sc o p y El ec tr o n m ic ro sc o p y Super- resolution microscopy 1 cm Frog egg7 Rough ER Smooth ER Centrosome CYTOSKELETON Microfilaments Microtubules Peroxisome Lysosome Golgi apparatus Ribosomes
In animal cells but not plant cells:
Lysosomes Centrioles Flagella (in some plant sperm)
NUCLEUS
Intermediate filaments
ENDOPLASMIC RETICULUM (ER)
Mitochondrion Plasma membrane Figure 6.9
endoplasmic reticulum
nucleus
mitochondrion
lysosome
Golgi apparatus
cytosol
ribosomes
cytoskeleton
You should
know everything
in Fig 6.9
8 Rough ER Smooth ER Centrosome CYTOSKELETON Microfilaments Microtubules Peroxisome Lysosome Golgi apparatus RibosomesIn animal cells but not plant cells:
Lysosomes Centrioles Flagella (in some plant sperm)
NUCLEUS
Intermediate filaments
ENDOPLASMIC RETICULUM (ER)
Mitochondrion Plasma membrane Figure 6.9
Nucleus
9Nuclear envelope
Figure 6.10 Nucleus Nucleus Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membranePores
Rough ER Pore complex Surface of nuclear envelope.Pore complexes (TEM). Nuclear lamina (TEM). Close-up of nuclear envelope Ribosome 1 !m 1 !m 0.25 !m 10
– Carry out protein synthesis
ER
Cytosol
Free Ribosomes
Membrane Bound
Ribosomes
Large subunit Small subunit TEM showing ER and ribosomesDiagram of a ribosome 0.5 !m
Figure 6.11
RNA
&
Protein
Complex
Make Proteins to be Exported Make Cytoplasmic Proteins
Ribosomes
11 Rough ER Smooth ER Centrosome CYTOSKELETON Microfilaments Microtubules Peroxisome Lysosome Golgi apparatus RibosomesIn animal cells but not plant cells:
Lysosomes Centrioles Flagella (in some plant sperm)
NUCLEUS
Intermediate filaments
ENDOPLASMIC RETICULUM (ER)
Mitochondrion Plasma membrane Figure 6.9
Endoplasmic
Reticulum
Golgi apparatus
Ribosomes
12 4 5 6Nuclear envelope is
connected to ER
NucleusRough ER
Smooth ER
Golgi
transport vesicles
Golgi pinches off Transport Vesicles, Lysosomes, etc.
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3 2
Figure 6.16 Plasma membrane expands
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Smooth ER
• Synthesis of
membrane lipids
• Synthesizes steroids
• Stores calcium
• Detoxifies poison
14Rough ER
• Synthesis of
– secreted proteins
– membrane proteins
Has attached ribosomes
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Adds
oligosaccharides
(glycosylation)
16Cis
Golgi
Close
To Rough
ER
Trans
Golgi
Away
From
Rough
ER
Golgi Apparatus:
protein secretion
Processing, packaging and sorting center
17 NUCLEUS Figure 6.9
Mitochondria
(and
chloroplasts
)
18Mitochondria:
Powerhouses of the cell
19 Chloroplast
Chloroplast
DNA
Ribosomes StromaInner and outer membranes
Thylakoid
1 !m Granum
Chloroplasts
capture
energy from the sun
Photosynthesis
Sunlight -> ATP, Sugar
20 Rough ER Smooth ER
Lysosome ENDOPLASMIC RETICULUM (ER)
Figure 6.9
Lysosome
(animals only)
Peroxisome
21 Rough ER Smooth ER CYTOSKELETON Microfilaments Microtubules NUCLEUS Intermediate filamentsENDOPLASMIC RETICULUM (ER)
Figure 6.9
Cytosol
Cytoskeleton
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There are three
types of
fibers that
make up the
cytoskeleton
Table 6.1
Microtubules
Microfilaments
Intermediate
Filaments
Tubulin
25 mM dia
Actin
7 mM dia
various
8-15 mM dia
Cell shape
Organelle movt
Chromosome
separation
Flagellar mvt
Cell shape
Cell cleavage
Cytoplasmic
streaming
Muscle contract
Nuclear
lamina
Tension
bearing
elements
Anchors
Motors:
Dynein
Kinesin
Motors:
Myosin
23Movement of Vesicles along Microtubules
Vesicle ATP Receptor for motor protein Motor protein (ATP powered) Microtubule of cytoskeleton
(a) Motor proteins that attach to receptors on organelles can “walk”
the organelles along microtubules or, in some cases, microfilaments.
Microtubule Vesicles 0.25 !m
(b) Vesicles containing neurotransmitters migrate to the tips of nerve cell
axons via the mechanism in (a). In this SEM of a squid giant axon, two vesicles can be seen moving along a microtubule. (A separate part of the experiment provided the evidence that they were in fact moving.)
Figure 6.21 A, B
What evidence do
we have that
they actually
move?
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Three kinds of Movement
• Filament anchored
: motor “walks” along
filament (transport vesicles)
• Motor anchored
: filament moves (muscles)
• Both anchored
: bending (cilia and flagella)
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Motor MAPs transport vesicles
MTOC
Dynein
inbound
outbound
kinesin
27 Fig. 6-24 0.1 !m! Triplet!(c) Cross section of basal body! (a)!Longitudinal section of cilium! 0.5 !m! Plasma membrane! Basal body! Microtubules! (b)!Cross section of cilium! Plasma membrane! Outer microtubule doublet! Dynein proteins! Central microtubules! 0.1 !m!
Cilia and Flagella
Have 9+2 arrangement of microtubules
and motor proteins.
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CYTOSKELETON Ribosomes (small brown dots)
Central vacuole/Tonoplast Microfilaments Intermediate filaments Microtubules Rough endoplasmic reticulum Smooth endoplasmic reticulum NUCLEUS Chloroplast Plasmodesmata Wall of adjacent cell
Cell wall Golgi apparatus Peroxisome Plasma membrane Mitochondrion Figure 6.9
Plants have 2 other support
mechanisms
• Cell Wall
• Vacuole or
Tonoplast
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Central Vacuoles (Tonoplasts)
– Only in plants
Central vacuole Cytosol Tonoplast Central vacuole Nucleus Cell wall Chloroplast 5 !m Figure 6.15Acts like a “balloon in a
box”
to hold plant cells
rigid
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