1. Moving Cellular Materials
Types of Transport

2. Cell membrane The cell membrane is referred
to as semi-permeable because
it allows some substances to enter
the cell while keeping other out
of the cell.
It is made of two phospholipid
layers.
The head of the lipids are
hydophilic (attracted to water).
The tails are hydrophobic (afraid of
water).

3. Part I. Passive transport
Passive transport is a type of transport that moves materials through the membrane that DOES NOT require energy.
All materials pass from an area of
high concentration to an area of low
concentration. This means materials
go with the concentration gradient.
This would be like traveling down
stream in a boat.

4. Types of Passive Transport
There are three types of transport:
diffusion,
osmosis, and
facilitated diffusion.
All three will be explained in the following slides.

5. Oxygen and other small gas molecules use this type of transport.
The random movement of molecules from an area of high concentration (where there is relatively more of them) to an area of low concentration (where there is relatively less of them).
Oxygen and other small gas molecules use this type of transport.
Diffusion

6. Equilibrium
Molecules of a substance will continue to move until the relative number of molecules is equal in the two areas.
Equilibrium is the equal balance of molecules between two areas.

7. Osmosis Osmosis is the diffusion of water through the membrane.
Water moves from an area
of high concentration of
solute to an area of low
concentration of solute.

8. From which side will the move? Why?
Side A Side B

9. Different Movements of Water
Hypotonic: the solute concentration is high inside the cell and water must move inside the cell
Hypertonic: the solute concentration is high outside the cell and water must move out
Isotonic: the solute concentrations are the same inside and outside the cell; no net water movement

12. Facilitated Diffusion
The diffusion of larger molecules
(like glucose) across the membrane
with the help of transport proteins.
Molecules move from
high to low
concentrations.

14. Part II. Active Transport
Active transport is when energy (ATP) is required to move molecules across the cell membrane. The reason energy is required is because molecules move from low concentration to high concentration gradients.
This would be like trying to return to
your stadium seat to get your jacket
when thousands of fans are leaving.

15. Moving Molecules with Energy
Active transport moves
individual molecules like
minerals in the soil.
Minerals move into the
root system of plant
even if the roots contain
more minerals than the
surrounding soil.

16. Endocytosis
Endocytosis is the process of taking large substances into the cell by surrounding it with the cell membrane. Large protein molecules, food molecules, and even bacteria use this form of transport.

17. How does it work?
1. The cell membrane folds itself around the item, enclosing it in a sphere called a vesicle.
2. The vesicle pinches off and enters the cytoplasm.
3. The vesicle transports the substances to the part of the cell that needs it.

19. Exocytosis
The opposite of endocytosis, exocytosis is when the vesicles fuses with the cell membrane and its contents are released outside the cell.