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
10/13, 10/14
 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 Cell membrane
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
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
Continued cell organelles
Organelle
Cytoplasm
Plant cell or Both
both
Function
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
Continued cell organelles
Cell organelle
Plant cell or both
function
Endoplasmic Reticulum
(Rough)
Both
Serves as the cell’s transport
system, transports proteins
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
Cytoskeleton
Both
In plants only, also used to
support heavy structures
such as leaves and flowers.
Acts as a scaffold to provide
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