1. With your table partner answer these questions:
1. In order for a cell to survive, what substances might need to
get into a cell or out of a cell?
2. What structure do things need to get past in order to get in or
out of cells?
3. Would it be easier for you to get to a place by walking with
the wind or against the wind? Up hill or down hill?

2. In order to understand the transport of materials in
and out of the cell we will focus on the barrier
between a cell and its environment. Do you know
what that barrier is?
• Why yes of course, it is the cell membrane!

3. First let’s take a closer look at a
soap bubble, why?

4. Note how the surface is not static.
It swirls and moves freely.

5. Or consider the molecules in the
membrane sort of like a ball pit.
They can move around.

6. THINGS NEED TO PASS THROUGH THE
Cell Membrane
DOUBLE LIPID LAYER
The cell membrane is made up a __________________________.
Phospholipids have a head that is attracted to water
_____________________ and a tail that repels waterHYDROPHOBIC
HYDROPHILIC ___________.

7. In the cell, there are 2 layers of phospholipids. As you can see
in the drawing below, the 2 layers of lipids have the “heads”
facing outward toward the water, and the “tails’ facing inward
where there is no water. This double layer of phospholipids
MEMBRANE
forms a tough yet flexible _________________.

8. Protein channels
Also located within the lipid bilayer are ____________________
and ____________________ chains..
carbohydrates
The proteins
can act as The carb
channels or chains
pumps. identify the
cell as
They also belonging to
identify your you. They
cells and are like little
sometimes act labeling
as receptor sites. If a cell enters your and has different
flags.
carbohydrate chains, the white blood
cells will attack them because they
are foreign invaders of your body.

9. So how does stuff move in and
out of a cell?
• In some cases it moves very easily by
following a concentration gradient.
• What the heck is that?

10. A situation in which particles are highly concentrated in one area
and in low concentration elsewhere.

11. PASSIVE TRANSPORT: Movement of small particles across a
membrane WITHOUT USING ENERGY!
DIFFUSION FACILITATED
OSMOSIS DIFFUSION
Random movement
of particles from THINK “H2O-
areas of high to low smosis”
Allows larger
concentration
Movement of water particles to get
from high to low through by using
concentration protein channels

12. THE KEYS THINGS ABOUT PASSIVE TRANSPORT ARE
1- THEY DO NOT REQUIRE ENERGY
and
2- THE THREE TYPES ARE: diffusion, osmosis, and facilitated
diffusion.

13. OSMOSIS
DIFFUSION OF WATER.
What makes this type of diffusion have a special name?
•It is for WATER
• Diffusion is general, osmosis is specific
•Water must cross a membrane
In organisms, osmosis transports
water INTO or OUT OF cells.

14. This stuff is so fascinating, let’s
watch a cool movie on it.

15. KEY POINT TO REMEMBER:
IN OSMOSIS, WATER WILL
ALWAYS ALWAYS ALWAYS MOVE
FROM AN AREA WHERE IT IS
HIGHLY CONCENTRATED TO AN
AREA OF LOW CONCENTRATION.

16. WHAT TYPE OF CELLS HAVE CELLS WALLS?
If there is a lot of water entering a plant’s cells by osmosis, it has a
lot of water pressure pushing out on the cell walls. This type of
water pressure is called
EXAMPLES OF HIGH
AND LOW TURGOR
PRESSURE:
Notice the cell wall and
the cell membrane.

17. The environment in which a cell resides
The solution in which the cell is exposed to (its
environment) will either make it shrink, swell, or stay
the same. There are 3 types of solutions it can be in:
hypotonic, hypertonic, and isotonic.
Below; beneath; under
HYPO means…
Less than normal; deficient
HYPER means… Over; above; beyond
Excessive; excessively
ISO means… Equal

18. LAB TIME
Let’s explore some cells in different environments.

19. HYPOTONIC
.
Solutions that have a LOWER amount of water inside the
cell than outside the cell.
•Water moves into cell from solution
•Cell expands (and may burst) = CYTOLYSIS

20. MORE HYPOTONIC
SOLUTIONS
CYTOLYSIS: The swelling of a cell due to water moving into the
cell.

21. HYPERTONIC SOLUTIONS
Solutions that have a HIGHER amount of water inside the
cell than outside the cell.
•Water moves out of the cell into the solution
•Cell shrinks - plasmolysis

22. MORE HYPERTONIC
SOLUTIONS
PLASMOLYSIS: The water loss due to water moving out of the
cell to a lower concentration. Cell will shrink.

23. ISOTONIC SOLUTION
Solutions that have an equal amount of water inside the
cell and outside the cell.
EQUILIBRIUM: Equal amounts of water move in and out of cell.

24. Facilitated Diffusion
Only very very very small particles can get
through a cell membrane by diffusion. A cell has
another way of getting bigger ones inside.
Facilitated diffusion allows larger particles to
enter the membrane by diffusion. There are
PROTEIN CHANNELS
_____________ _______________ within the cell
membrane that act as tunnels that let them in.
When a particle gets inside the cell through these
channels, it is called facilitated (helped) diffusion.

25. PASSIVE TRANSPORT IN ACTION: Facilitated diffusion for
bigger particles
Molecules will randomly move through the opening in a process
called diffusion. This requires no energy, molecules move from an
area of high concentration to an area of low concentration.
REQUIRES NO ENERGY

26. Processes where something gets into
or out of the cell by a procedure which
uses ENERGY!
There are 3 types of active transport:

27. PUMPS
If a particle needs to get into or out of the cell against the
concentration gradient, it will need to use ENEGY. This means
that the particles need to go from an area of LOW concentration to
an area of HIGH concentration.
THEY ARE MOVING AGAINST THE CONCENTRATION
GRADIENT!
Within the cell membrane are PROTEINS that have channels
which act as pumps.
Let’s take a look at a pump in action

28. PUMPS in action
Some proteins actively use energy from the ATPs in the cell to drag
molecules from area of low concentration to areas of high concentration
(working directly against diffusion) an example of this is the
sodium/potassium pump. Here the energy of a phosphate (shown in red)
is used to exchange sodium atoms for potassium atoms.

29. Large Particle Movement
Sometimes larger things need to enter or exit
the cell, but they cannot fit through a
protein channel. They will enter or exit by
endocytosis or exocytosis.
ENDOCYTOSIS: Cell surround an object and engulfs it within
the membrane and forms a vacuole.

30. The cell membrane can also engulf structures that are much too
large to fit through the pores in the membrane proteins this process
is known as endocytosis. In this process the membrane itself wraps
around the particle and pinches off a vesicle inside the cell. In this
animation an ameba engulfs a food particle.

31. EXOCYTOSIS
The cell pushes a vacuole to its surface, the
vacuole opens and the object is expelled.
Large molecules that are manufactured in the cell are released through
the cell membrane.

32. EXAMPLES of ENDO:
White blood cells
Amoeba engulfing paramecium
EXAMPLES of EXO:
Cells expelling waste
•Exocytosis (animation) click for movie link

33. THE END