Cellular Transport
How do cells move nutrients, products
and wastes in and out of the cell?
Why is this traffic across the membrane
so important?
Cells are filled and surrounded
by watery fluid.
This fluid helps
solids move around
inside, outside the
cell and cross the
cell membrane.
Cell Membrane
The cell membrane
controls what moves
in and out of the cell.
Semi-permeable membrane
Cell membranes only allow
some solutes (solids) to
move across it.
Movement across the
membrane depends on size
and type of the solute
(solid).
Membranes are just so beautiful!!!!!
Types of Transport
High
concentration
Low
concentration
Low
concentration
Down the
concentration gradient
High
concentration
Up the
concentration gradient
Summary: Types of Transport

Passive Transport




Molecules move from area
of high concentration to
area of low concentration
Movement is down the
concentration gradient
No energy needed
Small molecules such as
H2O, O2 and CO2

Active Transport




Molecules move from area
of low concentration to
area of high concentration
Movement is up the
concentration gradient
Energy is required (ATP)
Large molecules, ions
Diffusion –
molecules move from area of
high concentration to area of low concentration.
Osmosis –
water moves across membranes
(diffuses) to where there is less water.
Concentrations affect Osmosis
Water moves
out of the cell
Water moves
across
membrane
(in/out) at
equal rates.
Water
moves into
the cell
Red Blood Cells
in Hypertonic solution (video)
Plants and Osmosis
Hypertonic solution (video)
Concentrations affect osmosis
higher amount of
solute outside
cells
equal amount of
solute in and out
of cells
lower amount of
solute outside
cells
Let’s Review
Solution is made of solutes dissolved
in a liquid or gas.
Hypertonic Solution = high amount
of solutes
Hypotonic Solution = low amount of
solutes
Isotonic Solution = equal amount of
solutes
Dynamic Equilibrium is reached
when solutes and water move
across a membrane at equal rates
because concentrations are equal
(isotonic).
Homeostasis = all living systems
need to maintain perfect
concentrations inside each cell
Test your knowledge
On your left side, number 1-14 (short
answer)
15 and 16 Extended answers required
1. Which side is hypertonic? A
2. Why?
Lower
concentration
of solute (sugar)
B
A
Higher
concentration
of sugar
B
Same concentration
of sugar
3. Can the solutes fit across
the membrane?
4. How can you describe the
membrane since it is very Selectively
memselective about what can permeable
brane: sugar molecules cannot pass
move across?
through pores, but
Water molecules
cluster around
sugar molecules
water molecules can
5. How can both sides reach
equilibrium?
More free water
molecules (higher
concentration)
Fewer free water
molecules (lower
concentration)
Osmosis

Water moves from an area of higher
free water concentration to an area
of lower free water concentration
ENVIRONMENT
10% NaCL
90% H2O
NaCL
(salt is ionic,
cannot pass through
membrane without energy)
CELL
?
10% NaCL
90% H2O
6. What is the direction of water
movement?_________
7. Describe the solution outside the cell. ________
8. Describe the solution inside the cell. __________
10% NaCL
90% H2O
CELL
?
20% NaCL
80% H2O
9. What is the direction of water movement?________
10. Describe the solution outside the cell. ________
11.Describe the solution inside the cell. __________
15% NaCl
85% H2O
CELL
?
5% NaCl
95% H2O
12. What is the direction of water movement?_______
13. Describe the solution outside the cell. ________
14. Describe the solution inside the cell. __________
15.How do cell move nutrients, products and wastes in
and out of the cell?
16. Why is this traffic across the membrane so
important?
Demo Lab
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-
-
Materials
Celery sticks in
different salt
solutions???
Iodine solution /
starch solution???
Potato cores in
different salt
solutions???
Procedure
Cell membrane
tendency of any molecule to spread out into available space
Selectively permeable
diffusion of a substance across a biological membrane
Hypotonic
These help transport things across the membrane
Hypertonic
lower concentration of solutes
Isotonic
passage of molecules and ions with transport proteins across a
membrane down the concentration gradient
Passive transport
movement of a substance against its concentration gradient with
the help of cellular energy
Diffusion
Membrane only allows certain things across
Concentration gradient
Barrier made up of phospholipids and proteins that controls what
enters and exits the cell
Solution
Solute
Equilibrium/Homeostasis
Active transport
When there are two different concentrations across a membrane.
Molecules always move from high to low concentration without
energy (ATP)
equal concentrations of solutes
the diffusion of water across a selectively permeable membrane
Membrane proteins
control of water balance
Osmosis
Combination of a solvent and a solute equally mixed
Osmoregulation
Molecule used in living systems for energy
Facilitated Diffusion
ATP
State where molecules move across the membrane at equal rates
A substance being dissolved in another
higher concentration of solutes