The Cell Theory & Cell Structure
Chapter 3, sections 1 and 2
The Cell Theory
• All living things are made of cells
• Cells are the basic unit of structure &
function
• All cells come from pre-existing cells
Scientists and their Contributions
• 1655 – Robert Hooke coins the term “cell”
after viewing cork under an early
microscope
A drawing
of Hooke’s
cork cells
Hooke would
have used a
microscope
like this 
Scientists and their Contributions
• 1674 – Anton van Leeuwenhoek
observes the first living cells
under a microscope
Scientists and their Contributions
• 1838 – Matthias Schleiden determines that
all plant tissues are made of cells
• 1839 – Theodor Schwann determines that
all animal tissues are made of cells
Scientists and their Contributions
• 1855 – Rudolf Virchow asserts that every
cell comes from a pre-existing cell
Prokaryotes vs. Eukaryotes
Characteristic
Prokaryote
Eukaryote
Outer
boundary
Cell wall and
cell membrane
always
present
Nucleus
NO
Cell
membrane
always; cell
wall
sometimes
YES
Prokaryotes vs. Eukaryotes
Characteristic
Prokaryote
Eukaryote
DNA
YES
YES
Ribosomes
YES
YES
Prokaryotes vs. Eukaryotes
Characteristic
Prokaryote
Eukaryote
Other organelles NO
YES
Kingdoms
(classification)
Protista, Fungi,
Plantae,
Animalia
Eubacteria,
Archaebacteria
Prokaryotes vs. Eukaryotes
• Prokaryotes: cell that does not have a
nucleus or any other membrane-bound
organelles
• Eukaryotes: cell that does have a
defined nucleus and other membranebound organelles
Plants vs. Animals
Characteristic
Plants
Animals
Outer boundary Cell wall and
Cell membrane
cell membrane only
Nucleus
YES
YES
Plants vs. Animals
Characteristic Plants
Animals
DNA
YES
YES
Mitochondria
YES
YES
Plants vs. Animals
Characteristic Plants
Animals
Chloroplasts
YES
NO
Vacuoles
One large,
Many smaller
central vacuole vacuoles
throughout
Plants vs. Animals
Characteristic Plants
Animals
Trophic role
heterotrophic
(consumer)
autotrophic
(producer)
Kingdom
Plantae
(classification)
Animalia
Cells vary between and within organisms.
• Cells come in all sizes ex: bacterial cells
are much smaller than a typical animal
cell
• Some cells may have differences based
upon their requirements ex: cells that
need to produce lots of energy, like
muscle cells, might have more
mitochondria (since mitochondria are the
“powerhouses” of the cell).
Key Organelles
(1) Nucleus – control
center of cell;
contains
deoxyribonucleic
acid (DNA);
enclosed by a
nuclear membrane
with pores; only in
eukaryotes
Key Organelles
(2) Ribosomes – site
of protein synthesis
some are freefloating, some are
attached to rough
ER
Key Organelles
(3) Endoplasmic
reticulum –
“highway” of cell;
provides path for
other substances
to travel along;
may be smooth
(w/o ribosomes) or
rough (w/
ribosomes)
Key Organelles
(4) Golgi
Apparatus –
“post office” of
cell; modifies
and packages
protein & lipids
before they are
sent out of the
cell
Key Organelles
(5) Mitochondria –
“powerhouse” of cell;
converts food energy
into chemical energy
(ATP); has a double
membrane and its
own DNA (which can
be considered
evidence of
endosymbiosis)
Key Organelles
(6) Lysosomes –
enzyme-filled sacs
that digest cellular
wastes
Key Organelles
(7) Chloroplast – site of
photosynthesis;
converts solar/light
energy into sugar
(glucose); found in plant
cells, some bacteria,
and some protists; has
a double membrane
and its own DNA (which
can be considered
evidence of
endosymbiosis)
Key Organelles
(8) Vacuoles – storage
tank; primarily for
water but also holds
some minerals and
other dissolved solids;
plant cells have one
large central vacuole
while animal cells
multiple, smaller
vacuoles
Make sure you can…
• Label the key organelles on a plant and /
or animal cell diagram!
• Compare and contrast:
– Prokaryotes and Eukaryotes
– Plant and Animal cells