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The Endomembrane System
Rough ER
Transport
vesicle from ER
Golgi
apparatus
Secretory
vesicle from Golgi
Vacuole
Secretory
protein
Lysosome
Plasma membrane
The Endoplasmic Reticulum
– Produces an
enormous variety
of molecules
– Is composed of
smooth and rough
ER
Nuclear
envelope
Ribosomes
Rough ER
Smooth ER
The Endoplasmic Reticulum
After the rough ER synthesizes a molecule it packages
the molecule into transport vesicles
4
Transport vesicle
buds off
Ribosome
3
Secretory
protein inside
transport
vesicle
Protein
1
2
Rough ER
Polypeptide
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The Golgi Apparatus
– Works in partnership with the ER
– Refines, stores, and distributes the products of cells
Transport
vesicle
from ER
“Receiving” side of
Golgi apparatus
Golgi apparatus
New vesicle forming
Transport vesicle
from the Golgi
“Shipping” side of
Golgi apparatus
Plasma membrane
Lysosomes
• A lysosome is a membrane-enclosed sac
– It contains digestive enzymes
– The enzymes break down macromolecules
– They break down damaged organelles
Lysosome
Digestion
Damaged
organelle
(b) Lysosome breaking down damaged organelle
Vacuoles
Vacuoles are membranous sacs
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Cellular energy conversion
Mitochondria are the sites of cellular respiration,
which involves the production of ATP from food
molecules
Outer
membrane
Inner
membrane
Cristae
Matrix
Space between
membranes
Figure 4.18
Cytoskeleton
● Provides
mechanical support to
the cell and maintain
its shape
*microtubules
The Cytoskeleton
*microfilaments
(actin
( ti filaments)
fil
t)
*intermediate
filaments
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Microfilaments
Microtubules
*centrosome
*centrioles
Cilia and Flagella
Cilia and flagella are motile appendages
• Flagella propel the cell in
a whiplike motion
• Cilia move in a coordinated
back-and-forth motion
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Cilia and Flagella
“9 + 2”
basal body
The Cytoskeleton
dynein – motor molecules
Plant Cells
Not in animal cells
Cytoskeleton
Mitochondrion
Central
vacuole
Nucleus
Cell wall
Rough endoplamsic
reticulum (ER)
Chloroplast
Ribosomes
Plasma
membrane
Smooth
endoplasmic
reticulum (ER)
Plasmodesmata
Golgi apparatus
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Plant Cells
Plant cells are encased by cell walls
Walls of two adjacent
plant cells
Vacuole
Plasmodesmata
(channels between cells)
Chloroplasts
Chloroplasts are the
sites of photosynthesis,
the conversion of light
energy to chemical
energy
Inner and outer
membranes of
envelope
Granum
Space
p
between
membranes
Stroma (fluid in
chloroplast)
Origin of Eukaryotes
6