Agenda
Daily Trivia
 Agenda
 Egg lab
 Notes
 Homework

Cellular Transport
Osmosis and Diffusion!
Ch. 8
See how it flows!
Vocab Review

Concentration = density of particles
Permeable = allows things to pass through
 Selectively Permeable = allows certain
things only to pass through
 Impermeable = allows nothing to pass
through

Solute = you add
 Solvent = added to

IMPORTANT DEFINITIONS
DIFFUSION: movement of particles from
higher concentration to lower
concentration
 OSMOSIS: diffusion of water across a
selectively permeable membrane

In a cell, water always tries to reach an equal
concentration on both sides of the
membrane!
DIFFUSION
It’s all Greek to me!
OSMOSIS comes from the Greek word
osmos, which means “pushing.” Osmosis
can push out a cell’s plasma membrane!
It’s so pushy!
OSMOSIS
What controls OSMOSIS?
1)
A concentration gradient (unequal
distribution of particles on each side of a
membrane) [p. 202]
During osmosis, only water
diffuses across the selectively
permeable membrane.
OSMOSIS
Homework

Osmosis/Diffusion
Worksheets
Daily Trivia

Challenger Deep, part
of the Mariana
Trench, is the
deepest part of the
ocean.

It is 35,838 ft deep
(that is almost 7
miles)
Gotta love the Greeks!
ISOS=equal
HYPO=under
HYPER=over
Remember your roots!
Hypotonic Solution



A cell is placed in pure
water
There is a lower
concentration of
solutes (dissolved
substances )outside the
cell than inside the cell.
Water will flow into the
cell.
Isotonic Solution



Equal concentrations of
solutes inside and
outside the cell.
Water will flow into and
out of the cell at equal
rates (dynamic
equilibrium)
EX: Immunizations are
isotonic solutions so
they do not damage the
cells by gain or loss of
water.
Hypertonic Solution



A cell is placed in a
concentrated salt
solution (seawater)
There is a higher
concentration of
solutes outside the cell
than inside the cell.
Water will flow out of
the cell
Note: These are animal red blood cells.
The size of the arrows indicates the magnitude and
direction with which water moves.
Homework


Letters to parents
Finish projects
Daily Trivia

A goldfish (like
most marine fish)
can survive in a tank
full of human blood.
Cellular Transport
Move it along, folks…
Cellular Transport
Passive Transport:
Molecules pass through the membrane by
diffusion requiring no extra energy.
 Ex: water and lipids

Passive Transport
Facilitated Diffusion:

passive transport across membrane with help
of transport proteins.

Ex: sugars

“Water Wheel”
Facilitated Transport
Active Transport: ENERGY
REQUIRED!

= movement of materials through a
membrane across a concentration gradient.

This requires energy to counteract the
movement of diffusion from high to low
concentrations!

Energy is in the form of ATP
What is ATP?

ATP = Adenosine TriPhosphate

Energy transfer molecule

Created in the mitochondria

Re-chargable battery
1)
How does active transport
work?
Transport protein called “carrier protein” binds
with particle of a specific shape
2)
Protein uses energy to move particle inside
3)
Particle is released into the cell
4)
Protein returns to original shape.
Active Transport
How carrier proteins work!
Active Transport
Cellular Transport
What about the big boys?

ENDOCYTOSIS: entering the cell

EXOCYTOSIS: exiting the cell

moving large masses of material

require energy (ACTIVE TRANSPORT!)
Endocytosis
Exocytosis
Homework

Diffusion problems (Review Session Friday AM)
ISOTONIC SOLUTIONS!




Concentration of dissolved substances in solution is
the same as concentration of dissolved substances
inside the cell.
Water inside cell is equal to water in solution.
Cells in isotonic solution do not experience osmosis
and retain their normal shape.
EX: Immunizations are isotonic solutions so they do
not damage the cells by gain or loss of water.
HYPOTONIC SOLUTIONS!





Concentration of dissolved substances is lower in
solution outside the cell than concentration inside
the cell.
There is more water outside the cell than inside.
Cells in hypotonic solutions experience osmosis in
which water moves through membrane into cell.
EX: In animal cells, the pressure inside cell
increases causing the cells to swell and sometimes
burst!
EX: In plant cells, the rigid cell wall prevents
bursting, but the cells become more firm.
CUCUMBERS IN THE MIST!
HYPERTONIC SOLUTIONS!





Concentration of dissolved substances outside cell
is higher than concentration inside cell.
There is more water inside cell than outside.
Cells in hypertonic solutions experience osmosis in
which water moves through membrane to
outside of cell.
Ex: In plant cells, membrane and cytoplasm
shrink away from cell wall and plant wilts.
EX: In animal cells, the pressure decreases and the
cells shrivel.
Don’t be so SALTY!