Transcript The Cell Theory – a timeline

The Cell Theory – a timeline
• Late 1500’s:
• Early 1600’s:
-first lenses used in Europe
-used to determine cloth
quality (weave and
precision)
-combos of lenses gave better
view
Leeuwenhoek uses
microscope to study nature
Early
1600’s
Early 1600’s
• Leeuwenhoek
• first to view pond
water organisms
• First to see living
microscopic orgs
• Made careful
sketches
Robert Hooke ( 1665)
• Used light
microscope to look at
thin slices of plant
tissues -- cork
• Looked empty, like
monk’s chamber
• Called tiny chambers
“cells”
Matthias Schleiden 1838
• German Botanist
(plants)
• All plants looked at
were made of cells,
so concluded:
“All plants are
made of
cells.”
Theodore Schwann -- 1839
• German scientist
who studied animals
-- zoologist
• Saw that all animals
he studied were
cellular so
concluded:
“All animals are
made of cells.”
Rudolf Virchow -- 1855
• German physician
who studied cell
reproduction
• “Where a
cell exists,
there must
have been a
preexisting
cell…..”
The Cell Theory
• All living things are composed of
cells
• Cells are the basic units of structure
and function in living things
• New cells are produced from existing
cells
Prokaryotes vs. Eukaryotes
• Prokaryotes:
• Eukaryotes:
*NO NUCLEUS
*Small and Simple – few
organelles
*Have cell membranes
and cytoplasm
Ex. Bacteria
*Contain nuclei
*Contains organelles that
perform specialized
functions
*Uni-or multicellular
Figure 7.4 A prokaryotic cell
Basic Cell Structures
• Cell membrane – thin, flexible
barrier around cell
• Nucleus – large, centralized structure
that contains genetic material and controls
cellular activities (brain of the cell)
• Cytoplasm – material inside membrane
(but not inside the nucleus) that supports the
internal cell shape and organelles
Basic cell parts: cell membrane and
cytoplasm
• Cell membrane –
*provides barrier between internal
and external environment of
cell
*is semi-permeable (some things
can go in, some cannot;
some things can exit, some
never can)
• Major job of cell membrane is to maintain
the cell’s environment – establish
homeostasis
Nucleus
•
•
•
•
Largest organelle
Enclosed by nuclear envelope or membrane
Nuclear membrane has pores in it
Contains inactive DNA
Cytoplasm
• Entire region between the nucleus and the
cell membrane
• The semifluid substance that fills this area is
called CYTOSOL, and this is what the
organelles are suspended in
Cell Wall
• Found in plant cells (another barrier in
ADDITION to the cell membrane)
• Protects the cell
• Gives support to cell
• Made of cellulose
• Is very porous and allows molecules to pass
through, but is NOT SELECTIVELY
PERMEABLE
Organelles
• Control:
*Nucleus
(plant and animal)
• Assembly, Transport, and Storage:
*Endoplasmic reticulum
*Ribosomes
*Golgi apparatus
*Vacuoles
*Lysosomes
(plant and animal)
(plant and animal)
(plant and animal)
(plant and animal)
(plant and animal)
• Energy transformations:
*Chloroplasts
*mitochondria
(plant only)
(plant and animal)
Endoplasmic reticulum –
“highway system”
• EXTENSIVE – accounts for more than half the
total membrane system in eukaryotic cells
• Name means “little net within the cytoplasm”
• Smooth and rough e.r. are actually connected, not
distinct, separate sections
• Job is to transport materials quickly from one
place to another in cell
Figure 7.11 Endoplasmic reticulum (ER)
Ribosomes
“protein factories”
• Sites of protein synthesis
• Cells with high rates of protein synthesis have MANY
ribosomes (human pancreas cell has MILLIONS of
ribosomes)
• Are “free” ribosomes in cytosol that make proteins for the
cell that they are INSIDE of
• Ribosomes that are attached to endoplasmic reticulum
(bound) are making proteins for packaging and export
OUTSIDE OF CELL
Figure 7.10 Ribosomes
Golgi apparatus
“Gift wrapper/UPS system”
• Finishes, sorts, ships cell products
• Golgi will modify products as needed
Figure 7.12 The Golgi apparatus
Vacuoles
“Bank Vaults” or “trash cans”
• Sites of storage in cells
*good things stored – water, minerals,
food etc.
*bad things stored – broken down cell
parts, waste
Lysosomes
“waste removal”
• Membrane-bounded sac of enzymes
• Lysosomes break down things
• Used in autophagy – recycle the cell’s own
organic material for use
Mitochondria and Chloroplasts
“powerhouses”
• Mitochondria – carry on cellular respiration
– sites of energy production in cell (glucose
broken down to produce ATP)
• Chloroplasts – carry on photosynthesis
– sites where sunlight, CO2 and water are
converted into glucose
Figure 7.17 The mitochondrion, site of cellular respiration
Figure 7.18 The chloroplast, site of photosynthesis
Cytoskeleton
“hay in mud makes bricks”
• Network of fibers extending into cytoplasm
of cell
• Provides structural support
Cilia and Flagella
“hairs and tails”
• Cilia are short projections from cell body –
hair-like
• flagella are much longer – whip-like
• Both facilitate MOVEMENT of the cell
Organelles do not work alone…
• Cell is a dynamic interaction of ALL of its
parts – literally, the basic unit of life….