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Cells
Early Contributions
• Robert Hooke - First person to see cells, he was
looking at cork and noted that he saw "a great many
boxes. (1665)
• Anton van Leeuwenhoek - Observed living cells
in pond water, which he called "animalcules" (1673)
• Theodore Schwann - zoologist who observed tissues of
animals had cells (1839)
• Mattias Schleiden - botanist, observed tissues of plants
contained cells ( 1845)
• Rudolf Virchow - also reported that every living thing is
made of up vital units, known as cells. He predicted that
cells come from other cells. (1850 )
Schwann, Schleiden, Virchow – Cell Theory
The cell theory
 1. All living things are composed of cells.
 2. Cells are the basic unit of structure
and function in living things.
 3. New cells are produced from existing
cells.
Characteristics of all cells
 Surrounded by cell membrane
 Contain DNA
 Contain cytoplasm
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Prokaryotic
 No nucleus
 Few internal
structures- have
simple ribosomes
 Smaller and simpler
than eukaroytic
cells
 One-celled
organisms,
Bacteria
http://library.thinkquest.org/C004535/prokaryotic_cells.html
Prokaryotic Cells
 Some use flagellum (Ex: whip) for
locomotion
– threadlike structures protruding from cell
surface
Bacterial cell wall
Rotary
motor
Flagellin
Sheath
Eukaryotic
 Have a membrane bound nucleus
 Contain organelles surrounded by
membranes
 Most living organisms – lots of variety
 Larger and more complex than prokaryotes
http://library.thinkquest.org/C004535/eukaryotic_cells.html
DIVERSITY OF LIFE
-Unicellular Organisms
-Multicellular Organisms
-Levels of Organization
Cells
Tissues
Organs
Organ Systems
Go to
Section:
Cell Wall
 Most commonly found
in plant cells & bacteria
 Supports & protects
cells
http://library.thinkquest.org/12413/structures.html
Cell Membrane
 Outer membrane of cell that
controls movement in and
out of the cell
 Double layer
 Plasma Membrane =
selectively permeable
boundary between the cell
and the environment
http://library.thinkquest.org/12413/structures.html
Plasma Membrane
Nucleus
 Directs cell activities
 Separated from cytoplasm by nuclear
membrane
 Contains genetic material – DNA
 Nickname: Headquarters or Brain
Nuclear Membrane
 Surrounds nucleus
 Made of two layers
 Openings allow
material to enter and
leave nucleus
http://library.thinkquest.org/12413/structures.html
Chromosomes/Chromatin
 In nucleus
 Made of DNA and
protein
 Contain instructions for
traits & characteristics
http://library.thinkquest.org/12413/structures.html
Nucleolus
 Inside nucleus
 Makes ribosomes
which then leave the
nucleus
http://library.thinkquest.org/12413/structures.html
Mitochondrion
Mitochondria
 Produces energy through
chemical reactions –
cellular respiration
 Converts glucose into
ATP
 Cristae – inner membrane
 Nickname: Powerhouse
of the cell
http://library.thinkquest.org/12413/structures.html
Chloroplast
 Found in plant cells only
 Contains green chlorophyll
 Where photosynthesis takes
place
http://library.thinkquest.org/12413/structures.html
Vacuoles
 Membrane-bound
sacs for storage,
digestion, and waste
removal
 Contains water
solution
 Help plants maintain
shape- large central
vacuole
http://library.thinkquest.org/12413/structures.html
Endoplasmic Reticulum
 Moves materials around
in cell
 Smooth type: lacks
ribosomes
 Rough type (pictured):
ribosomes embedded in
surface
 Nickname: Highway or
Subway of the cell
http://library.thinkquest.org/12413/structures.html
Cytomembrane System
Endoplasmic Reticulum (ER) = a system of
tubes and sacs formed by membranes (an
enclosed space)
a) Rough = with bound ribosomes
--transports proteins to the Golgi body
b) Smooth = without bound ribosomes
--functions in lipid synthesis, drug
detoxification
Lysosome
 Digestive sac for proteins,
fats, and carbohydrates
 Transports undigested
material to cell membrane
for removal
 Cell breaks down if
lysosome explodes
 Nickname: Trashcan or
Pac-Man of the cell
http://library.thinkquest.org/12413/structures.html
Centrioles
 Assemble microtubules during cell division
 Barrel shaped – pairs
 Found in animal cells
Golgi Bodies
 Protein 'packaging
plant’
 Nickname: FedEx or
Post Office of the
cell
 Modifies protein
– Attach
carbohydrates and
lipids to the protein
http://library.thinkquest.org/12413/structures.html
Vesicles move from ER to Golgi
Ribosomes
 Each cell contains
thousands
 Make proteins
 Found on Rough ER &
floating throughout the
cell
http://library.thinkquest.org/12413/structures.html
Cytoskeleton
Microtubules
Intermediate
filaments
Actin
Cytoskeleton
 Network of protein fibers supporting cell shape and
anchoring organelles
– Microfilaments
 Actin
 Cell movement
 Support of cell
– Microtubules
 Hollow tubes
 Movement of organelles
 Forms cilia, flagella, centrioles
Figure 7-7 Cytoskeleton
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Go to
Section:
Michondrion
“Typical” Animal Cell
http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif
“Typical” Plant Cell
http://waynesword.palomar.edu/images/plant3.gif
Venn Diagrams
Prokaryotes
Capsule
Animal Cells
Lysosomes
Go to
Section:
Cell membrane
Ribosomes
Cell wall
Plant Cells
Cell membrane
Ribosomes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Vacuoles
Mitochondria
Cytoskeleton
Eukaryotes
Cell Wall
Chloroplasts
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton