Transcript Methods of Movement in the Cell

Agenda
1. FA #12
2. Methods of Transportation Notes
p.133-134
3. Osmosis Lab (Handout)
4. Organelle Study Guide
5. Grab books, read section, and
complete objectives.
Methods of Movement in the Cell
Diffusion, Osmosis, & Active
Transport
p. 133-134 in binder
Cell Membrane
• Selectively Permeable “Gate Keeper”
– Some substances can pass through the
cell membrane while others cannot.
– Good things go into the cell, bad things
stay out
– Ex. Water, oxygen, carbon dioxide are
permeable but large molecules & salt stay
out
Cell Membrane
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
3 Methods of Moving Substances
In & Out of the Cell
• Diffusion
• Osmosis
• Active Transport
Diffusion
• Movement of molecules from an area in
which they are highly concentrated to an area
in which they are less concentrated.
• Ex. In one celled pond organisms, the oxygen
moves from the water into the cell.
Osmosis
• Diffusion/movement of water across a
selectively permeable membrane.
• Water moves from a high concentration
of water (less salt or sugar dissolved in
it) to a low concentration of water (more
salt or sugar dissolved in it).
Osmosis
Osmosis in Red Blood Cells
• Figure A: Red blood cells are in solution in which
concentration of water is the same as it is inside the cells.
(Normal)
• Figure B: RBCs are in water with high salt concentration.
• Figure C: RBCs are in water with very low salt
concentration, less than the cell salt concentration.
Passive Transport
• Riding a bike downhill doesn’t take any
energy to go fast, right?
• But pedaling your bike uphill does.
• Diffusion & Osmosis are like riding your bike
downhill.
– Movement from high to low concentration doesn’t
require energy.
• Passive Transport
– Movement of materials through a cell membrane
without using energy—highlow. (Diffusion &
Osmosis)
Active Transport
• What if a cell needs to take in a substance
that is in higher concentration inside the
cell than outside?
• The cell would have to move the
molecules in the opposite direction that
they naturally do. (Pedaling uphill)
• Active Transport
– Movement of materials through a cell
membrane that requires energy. Low High
Methods of Active Transport
Molecule to
be carried
• Transport Proteins
– Proteins “pick up”
molecules outside
the cell and carry
them in.
– Ex. Calcium (Ca),
Potassium (K), and
Sodium (Na)
Energy
Molecule
being carried
Methods of Active Transport
(cont.d)
• Transport by Engulfing
– Cell surrounds, or engulfs, a particle.
So…Why Is Movement of
Materials Important?
• All living things have certain
requirements they must satisfy in order
to remain alive.
– Exchanging gases (usually CO2 and O2),
– Taking in water, minerals, and food
– Eliminating wastes
• These tasks ultimately occur at the
cellular level, and require that molecules
move through the membrane that
surrounds the cell.
Why Are Cells So Small?
• As a cell’s size increases, more of its
cytoplasm is located farther from the cell
membrane.
• Once a molecule enters the cell it is carried to
its destination by streams of moving
cytoplasm.
• In a very large cell, the streams of cytoplasm
must travel farther to bring materials to all
parts of the cell.
• Much more difficult for molecule to reach
center of cell.
• Wastes need to be removed.
Summary
• Cell membrane is
– A complex structure that is responsible
for…
• Separating the contents of the cell from its
surroundings
• Controlling the movement of materials into and
out of the cell
• Cell movement occurs by…
– Diffusion, Osmosis, & Active Transport
Osmosis Lab
• Read through handout EXTREMELY WELL
• Complete Prelab on p.185.
• Perform the Lab
– Completed at your lab groups in 4’s.
– Supplies can be found on the back lab table.
– Cover cups with aluminum foil or saran wrap.
• Make sure that someone from your group will
come in on FRIDAY to get the completed
results.
Organelle Study Guide
1.
2.
3.
4.
5.
See example.
Fold outward flaps in.
Cut along dotted lines
Color organelle
Write function on the backside of the
flap.
6. Write name underneath the flap.