Download The Cell

The Cell
 Cell: the basic unit of living organisms
History
of
the
cell
History:
1665-Robert Hooke viewed thin slices of cork
under a crude microscope and observed tiny
hollow boxes. He called these boxes cells.
1674- Anton van
Leeuwenhoek observed
tiny living organisms in
drops of pond water
1838- Matthias Schleiden
concludes that all plants
are made up of cells.
1839-Theodor Schwann
concludes that all animals are
made up of cells.
1855-Rudolph Virchow
completes the cell theory. “
father of modern pathology”
 1970- Lynn Marguilis proposes
the Endosymbiont Hypothesis.
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.
 There are two types of cells:
prokaryotes and eukaryotes
Cell types: Prokaryote
Cell Type
Prokaryote
Description
Cells that have genetic material not
contained in a nucleus.
Example
Bacteria
Components
1.
Plasma membrane: controls
what enters or leaves the cell.
2.
Chromosome: contains the
DNA (the genetic info.)
3.
Ribosomes: make proteins.
Exception:
Ribosomes are not true organelles
because they are not enclosed in a
membrane.
Eukaryote
Cell Type
Description
Example(s)
Components
Eukaryote
Cells that contain a nucleus
in which their genetic
material is separated from
the rest of the cell.
Plants, Animals, Fungi,
Protists
See homework for the list
of organelles
Plant cells VS. Animal Cells
 Plant and animal cells differ in the following ways:
Type of Cell
Shape
Boundary
Vacuoles
Chloroplasts/
Plastids
Centrioles
Plant
Rectangular
Animal
Irregular or
roundish
Cell wall and Cell membrane
cell membrane only
One large
Several smaller
vacuole
vacuoles
Present
Absent
Absent
Present
How to Use a Microscope
STEPS FOR USING A COMPOUND
LIGHT MICROSCOPE
 1. Plug the microscope in, turn on the light and
place the slide on the stage.
 2. Start with the scan objective (the shortest
objective). The magnification is 4 X 10 = 40X.
(Magnification is determined by the objective X the
eyepiece.)
3. Adjust the diaphragm so the most light is allowed
through. (#5)
 4. Using the coarse adjustment knob (the biggest),
slowly focus so that the stage moves AWAY from the
objective until you just see image. You must do this
step VERY SLOWLY.
 5. Carefully move the slide until the image is
in the center of the field of view.
 NOTE: Moving the slide left will move the
image right and moving the slide up will
move the image down etc…
 6. Using the fine adjustment knob, (the smaller
knob) bring the image into focus.
 7. Without touching the adjustment knobs,
carefully switch to the low power objective (the
medium sized one). You should look to the side
while switching objectives. Magnification:
____________________.
 NOTE: YOUR IMAGE SHOULD BE IN THE FIELD OF
VIEW. IF NOT, START AGAIN AT THE BEGINNING.
 8. You should only need to do some fine
adjusting to bring the image into focus.
 10. Without touching the adjustment
knobs, carefully switch to the high power
objective (the longest one). Look to the
side again. Magnification:
____________________________
 11. You should only need to do some
fine adjusting to bring the image into
focus. WARNING: NEVER USE THE COARSE
ADJUSTMENT KNOB AT HIGH POWER
Cell organelles - link
Organelle
Plant cell or both
function
Cell (plasma)
membrane
Both
Controls the
movement of
materials that enter
and exit the cell
Nucleus
Both
Nuclear Envelope
Both
Nucleolus
Both
Chromatin
Both
Houses the DNA of the cell,
controls the functions of the
cell
Controls the movement of
materials that enter and
exit the nucleus
Produces ribosomes
Made out of DNA, stores
the genetic information for
the organism
Organelle
Continued
cell
organelles
Plant cell or Both
Function
Cytoplasm
both
The site of many
chemical reactions in
the cell
Mitochondria
Both
Lysosomes
Both
Breaks down food particles
to release energy
Digests excess or worn out
cell parts (contains digestive
enzymes)
Ribosomes
Both
Makes proteins
Endoplasmic Reticulum
(Smooth)
Both
Serves as the cell’s transport
system, site where lipids are
made
Cell organelle
Plant cell or both
function
Serves as the cell’s transport
ContinuedBothcell organelles
system, transports proteins
Endoplasmic Reticulum
(Rough)
Golgi Apparatus
Both
Receives, packages and labels
proteins and lipids for
delivery to other parts of the
organism
Vacuole
Both
Temporary storage of water,
food and waste
In plants only, also used to
support heavy structures
such as leaves and flowers.
Cytoskeleton
Both
Acts as a scaffold to provide
support for the organelles
Continued….
Cell organelle
Plant cell or both
function
Cilia p. 501
Animal
Short, numerous, hair-like
structures used in movement
Flagella p. 499
Animal
Longer whip-like structures,
usually only a few, used in
movement
Cell Wall
Plant
Supports and protects the
plant cell
Centrioles
Animal
Used during mitosis to
separate the chromosomes
Continued…….
Cell organelle
Plant cell or both
Chloroplasts
Plant
Plastids
Plant
function
Transform light energy in to
chemical energy and store
the energy in food (sugar)
Storage of starches, lipids,
and pigments in plants.
The Plasma membrane
 Function: to control the movement of substances into
and out of the cell.
Maintains homeostasis.
Plasma Membrane
 selectively permeable (allows some materials to
pass through while keeping other out).
 A.Phospholipid:
 Phosphate Head (hydrophilic): Water loving;
Contains phosphate * POLAR
 Fatty Acid Tail (hydrophobic): Water fearing;
 Contains fatty acids: saturated are rigid and
unsaturated are flexible * NONPOLAR
form a bilayer :phosphate heads
lined up on the outside
fatty acids tails on the inside of the
bilayer
Small nonpolar molecules are able
to pass right through the plasma
membrane. Ex: O2, CO2
Entering the cell
Polar molecules, ions or large
molecules are not able to pass
through the membrane. Ex: Na+, Cl-,
H+, Ca+, H2O
Polar molecules, ions and large
molecules can pass through the
membrane with the help of proteins.
Structure
B. cholesterol
 helps to give a little rigidity (to
strengthen) to the plasma
membrane
Structure
 C. proteins
 can be embedded in the membrane or located outside
the membrane
 carry out many different functions
 1. protein channels -used in diffusion.
 2. protein pumps-used in active transport.
 3. enzymes-speeds up reactions.
 4. receptor proteins-accepts certain molecules.
 5. marker proteins-where the carbohydrates are attached.
Structure:
D. carbohydrates
·
attached to marker proteins
· help in cell recognition so the body
can distinguish between foreign
substances
·
act like a “name tag”
·
called the glycocalyx
THE FLUID MOSAIC MODEL
Describes the plasma membrane.
 · The phospholipids are able to move
sideways around each other (fluid) but still
stay within the membrane.
 · The membrane is made up of so many
different molecules it is like a mosaic.
 · The dual-natured polarity of the
phospholipids maintains the structure of the
cell membrane.
 · The phospholipid bilayer is an example of
the fact that oil (fats) and water don’t mix!!!
 ·
 The lipid bilayer is held together by
the fact that the polar heads
(hydrophilic) are attracted to water
both inside and outside the cell.
 The fatty acid tails (hydrophobic) are
repelled by the water so they “hide”
inside the bilayer.
Model