The Cell
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All Living things are composed of cells
All Cells have/contain the following:
Cell Membrane - Lipid Bilayer - Separates inside from outside
Cytoplasm
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Cytoplasm - everything but
DNA/Nucleus
Two Cell types
Prokaryotic Cells
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1.
2.
3.
4.
5.
6.
Primitive cells – include bacteria
No nucleus
No Membrane-bound organelles
Very Small 1-10 micrometers
Single Strand of Circular “naked” DNA
Contain Ribosomes
Typical Prokaryotic Cell
Eukaryotic Cells
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1.
2.
3.
Eukaryotic Cells
1.
Contain a Nucleus which protects DNA /
Chromosomes
2. Much larger than prokaryotic cells
3. Have many different types of Membrane
bound organelles - compartmentalization =
efficiency
Eukaryotic Cells
Animal Eukaryotic
Cell
Plant Eukaryotic
Cell
Organelles
Membrane-Bound organelles only
found in Eukaryotes
 Localize Chemical Reactions making
the cell far more efficient
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Major Organelles of the Eukaryotic Cell
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The Nucleus
“eukaryotic” means “true
nucleus”
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Surrounded by a Nuclear
Envelope
Envelope is double layered
with an Inner & Outer
membrane
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Has perforations called
Nuclear Pores which allow
large molecules to pass
in/out of the nucleus
Contains a Nucleolus
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Contains & protects the
cell’s DNA
Helps coordinate the
division of cells
Ribosomes are made in this
region
Contains DNA packaged in
structures called
chromosomes
Chromosomes
Mitochondria
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Serves as the
“powerhouse
of the cell” by
generating
chemical
energy
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Has it’s own
DNA*
Can divide on
its own*
Chloroplasts (Plant Cell Only)
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Is the “cell’s farm” meaning food is
generated here.
Does this by
photosynthesis - the
conversion of CO2,
H2O and sunlight into
sugar
Contain Chlorophyll - a
green pigment - which
does this
Has it’s own DNA*
Can divide on its own*
Ribosomes
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Are NOT membranebound & also exist in
prokaryotes
Are used to
manufacture proteins
Granular in
appearance
Often found on
“rough” endoplasmic
reticulum*
Endoplasmic Reticulum
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Are folds of
membranes used to
package & modify
proteins made by
ribosomes. They
also make lipids
2 types
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“Rough” - which is
usually near nucleus
and covered with
ribosomes giving it
its “rough”
appearance.
(Finishes proteins)
“Smooth” - which is
usually away from
the nucleus
(produce lipids)
Examples of Endoplasmic
Reticulum
Smooth ER
Rough ER
Golgi Bodies
Are the post offices of
the cell
Modify (address) proteins
& lipids and send them
in packages (vessicles)
throughout (or out of)
the cell.
Lysosomes
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Small Vessicles
which serve to
digest particles and
clean-up cells
Contain Lysozyme –
a powerful digestive
enzyme
Digests food
particles
Destroys worn-out
organelles
Self-Destructs
worn-out cells
Centrioles
(Animal Cell Only)
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Serve as
construction/organization
points for cellular
microtubules
Organize and transfer
chromosomes and other
organelles during Meiosis &
Mitosis
Occur in some prokaryotes,
protists & animals. Do not
occur with fungi and plants
Tube like structures usually
at right angles to each other.
Some animals have centriolelike structures at the base
of flagella called basal
bodies.
Tonoplast
(water vacuole)
(plant cells only)
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Large H2O / Lipid /
waste storage tank
Provides pressure
(Turgor pressure) to
maintain cell
structure
Cell Wall
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Provides support /
protection for plant
cell
Two layers of cell
wall
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Primary Cell Wall
– Outer –
Cellulose only
Secondary Cell
Wall – Inner –
Cellulose & Lignin
Cell membrane is
innermost layer
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Network of fibers which
help organize the
internal arrangement
within cells.
Three basic types of
fibers compose
cytoskeleton:
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Actin Filaments
• Thinnest fibers ~7nM
• Formed from protein
Actin
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Microtubules
• Largest component of
cytoskeleton ~25 nM
• Formed from protein
Tubulin
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Intermediate filaments
• Intermediate in size
and can vary
• Form from several
proteins inluding
vimentin & keratin
Cytoskeleton