Cells
Robert Hooke -1665
• In his book, entitled
Micrographia,
Hooke was the first
to use the term cell
• From the Latin
“cella” meaning
“small chamber”
Anton van Leeuwenhoek1675
• A Dutch cloth
merchant who
became interested
in studying cells
• Was the first to see
and describe
bacteria, sperm
cells and protista
• Theodor Schwann (1838) – all
animals are composed of cells
• Matthias Schleiden (1838) – all
plants are composed of cells
• Rudolf Virchow (1856) “Omnis cellula e
cellula”
• “where a cell arises, there a cell must
previously have existed”
Modern Cell Theory
• All organisms are composed of cells.
• Cell come from other cells.
• Cells are the smallest unit of structure
and function in living organisms.
Prokaryotic Cells
• Lack a true nucleus
• Size: 1-10 microns
• Include bacteria
Basic Bacterial Cell
Examples of Prokaryotes
Eukaryotic Cells
• Have a true
nucleus
• Size: 10-100+
microns
• Include plants,
animals, fungi
and protista
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Cell Membrane – surrounds the cell
Cytosol – “cell liquid”
Organelles – “little organs”
Nucleus- control center
Cell Membrane
• Regulates the
passage into and
out of the cell
• Provides protection
• Helps in cellular
recognition of
molecules
Cytosol/Cytoplasm
• Cytosol: the liquid
portion inside the
cell membrane
• Cytoplasm: the
cytosol and
organelles, but not
the nucleus
Nucleus
Nucleus
• Contains DNA
• The cell’s “brain”
or CPU
• DNA codes for
protein production
• Surrounded by the
nuclear envelope
Cytoplasm
• Contains the cytosol and organelles
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Ribosomes
Endoplasmic reticulum
Golgi bodies or complex
Lysosomes
Mitochondria
Chloroplasts
Ribosomes
Ribosomes
• Are the cell’s
protein factories
• Read mRNA code
as seen on the right
• Maybe free in the
cytoplasm
• Or bound to the ER
Endoplasmic Reticulum
• Comes from the Greek Endo =
“within” Latin reticulum = “network.”
• A membrane network within the
cytoplasm
• Two types: Rough – with ribosomes
attached (RER)
• Or Smooth – with no ribosomes (SER)
Rough ER
• Helps the ribosomes
in the formation of
proteins
• Used to transport
proteins to other parts
of the cell
Smooth ER
• Functions include
synthesis of
membrane lipids &
detoxification of
drugs
• Liver cells contain
large amounts of
smooth ER
Golgi Body
Golgi Body
• Modify, sort, and
package proteins from
the ER for storage in
the cell & secretion
out of the cell
Lysosomes
Lysosomes
• Digestive sacs filled with
enzymes
• Breakdown lipids,
carbohydrates, and proteins
into a form that can be used
by the cell
• Digest worn out organelles
• Helps to recycle
cellular structures
• Sometimes called
“suicide sacs”
• Involved in
rheumatoid arthritis
• Example…
Mitochondria
• Converts chemical
energy stored in food
into compounds that
the cell can use
(cellular respiration)
• Contain their own
DNA
Chloroplasts
• Site of photosynthesis
• Contains the green pigment chlorophyll
• Helps to convert light energy, water, and carbon
dioxide into sugars
• Also contain genetic information
Endosymbiotic Theory
• States mitochondria and chloroplasts
were once free living prokaryotic cells
• First proposed in the 1890s, but not
supported until 1981 with the
discovery of mitochondrial DNA
• Explanation…
Vacuole
• Storage area for
water, salts, proteins,
and carbohydrates
• Many plants have a
large central vacuole
filled with liquid to
support the plant
Cell Wall
• The cell wall is a
rigid structure that
is found in plants,
fungi, and
bacteria cells
• It supports and
maintains the
shape of the cell. It
is extremely
strong.