Cell Transport Notes
(pp.33-37)
Copy the words seen in red onto your
note sheet.
Cell Membrane Review
- ALL cells have a cell membrane
made of proteins and lipids
- SOME cells have cell
membranes and cell walls
(plants, fungi and bacteria)
• The cell membrane is selectively
permeable which allows certain
substances such as oxygen,
water, food molecules, carbon
dioxide, and waste products to
move into and out of the cell.
Cell
Membrane
Cell Wall
Cell Transport
Materials move into and out of cells through
either passive transport or active transport.
Analogies for the 2 Types
of Cell Transport
Analogy: Child is
sitting on swing
and hoping that
the swing will
move without
assistance.
Analogy: Child is
being pushed on
the swing by a
helper.
Another Analogy for 2 Types of Cell Transport:
(A) PASSIVE TRANSPORTNO ENERGY NEEDED:
(1) Process of Diffusion
(2) Process of Osmosis
This was today’s
LL question!
(B) ACTIVE TRANSPORTENERGY NEEDED:
(1) Help of Transport Proteins
(2) Process of Engulfing
(or “Cell-Eating”)
(A) PASSIVE TRANSPORT
Molecules move from a more crowded to a less
crowded area to reach a balance, or
homeostasis, (equal amounts of the substance
on both sides of the membrane).
NO ENERGY is required.
Two Types of Passive Transport:
(1) Diffusion
(2) Osmosis
(1) DIFFUSION
Molecules (small particles) move from a more
crowded area to a less crowded area.
How does diffusion work?
Molecules bump into one another as they move and these collisions push the molecules
away from each other.
The more collisions, the more spread out the molecules become until they eventually
reach equilibrium (or homeostasis).
How does diffusion work?
Molecules bump into one
another as they move and
these collisions push the
molecules away from each
other.
The more collisions, the
more spread out the
molecules become until
they eventually reach
equilibrium (or
homeostasis).
(2) OSMOSIS
A special type of diffusion: Diffusion of water
through a selectively permeable membrane from a
more crowded area to a less crowded area
On the left,
the water
concentration
was high at the
start so the flow
of water moved
to the right.
The selectivelypermeable
membrane
allows water to
pass, but not
sugar.
Now you try
(before and after diffusion)
Diagram A: The oxygen molecules
( ) inside and outside the cell are
shown before diffusion.
Diagram B: You draw how the
oxygen molecules would be
distributed AFTER diffusion
has occurred.
If each molecule ( )was a molecule of water (instead of oxygen), could this
diagram be illustrating osmosis? Explain why or why not. (Remember there
are two conditions needed for osmosis) _____________________________
______________________________________________________________
______________________________________________________________
Now you try - ANSWER
(before and after diffusion)
Diagram A: The oxygen molecules
( ) inside and outside the cell are
shown before diffusion.
Diagram B: You draw how the
oxygen molecules would be
distributed AFTER diffusion
has occurred.
If each molecule ( )was a molecule of water (instead of oxygen), could this
diagram be illustrating osmosis? Explain why or why not. (Remember there
are two conditions needed for osmosis) Yes! Osmosis is the movement of
water through a membrane from high to low concentration so the
requirements would be met.
(B) ACTIVE TRANSPORT
Molecules move from a less
crowded to a more crowded
area WITH the use of
ENERGY. Molecules are
"carried" into or out of the
cell using some of the cell's
energy.
Two Types of Active Transport:
(1) Transport Pumps
(2) Engulfing (or “Cell-Eating”)
Example of a cell’s need for active transport:
Body cells must pump carbon dioxide out
into the surrounding blood vessels to be
carried to the lungs for exhale. Blood
vessels are high in carbon dioxide
compared to the cells, so energy is
required to move the carbon dioxide across
the cell membrane from LOW to HIGH
concentration.
outside of cell
inside of cell
Carbon Dioxide
molecules
(1) TRANSPORT PROTEINS
Proteins or Pumps are found in the cell
membrane. They transport molecules
across the membrane.
ATP =
Energy
(2) ENGULFING or “Cell-Eating”
The cell membrane surrounds the particle
and takes it in. The cell membrane forms a
vacuole around the particle.
Food is moved into the
cell by Endocytosis
Wastes are moved out
of the cell by
Exocytosis
Ex: Amoebas use this
process to eat.
Ex: White Blood Cells, which are
part of the immune system,
surround and engulf bacteria.