Cell Transport
Science 10
Section VIII
A. Introduction
 Every living organism must be able to
transport a huge amount of nutrients
and waste.
 The movement of wastes and
nutrients must be done in a liquid
medium. (Important to drink water)
All living things must do this to survive.
 1) Absorb nutrients and grow (eat)
 2) Have a system to convert energy
to a useable form (Digestion)
 3) Reproduce (divide cells)
 4) Get rid of waste!
B. Concentration Gradients
 High concentration of molecules in
one area compared to another. Eg.
Popping popcorn, perfume, koolaid.
 A concentration gradient is created
when a certain molecule is
concentrated in one area compared
to another.
Concentration Gradient
 Over time molecules will spread out
and become evenly spaced. Eg.
Koolaid over 48 hours example.
 This is called moving DOWN the
concentration gradient (moving from
an area of high concentration to an
area of low concentration.)
C. Diffusion
 Diffusion: when molecules randomly
move down the concentration
gradient (Kinetic energy!)
 There are six (6) factors that affect
the rate of diffusion…
Factors affecting Diffusion
 1) Temperature (hot temps increase
diffusion)
 2) Concentration (higher conc. the
more diffusion occurs)
 3) Phase (state): diffusion occurs
faster in a gas then a liquid, then
solid
Factors affecting Diffusion
 4) Pressure: higher pressure
increases diffusion
 5) Particle Mass: heavier the
particles (atomic mass) the harder
diffusion occurs
 6) Gate size: the larger the gate the
easier diffusion occurs.
Horseshoe Tubes
 Look in your notes about horseshoe
tube examples.
D. Mass Flow
 Sometimes another force is at work
to assist with Diffusion. A liquid
might be moved with a current,
gravity or pressure. (Stirring the
Koolaid)
 In your body your blood stream is an
example of Mass Flow!
E. Traffic Through Membranes
 Cell membrane are like bouncers at a
bar. They let certain things into the
cell while not allowing others in.
F. Types of Solutions
 There are three (3) types of solutions
that diffuse into and out the cell:
 1) Isotonic: solution with the same
concentration of solutes (particles
dissolved) as the solution it comes in
contact with.
 2) Hypertonic: solution with a
higher concentration of solutes.
Types of Solutions
 3) Hypotonic: solution with a lower
concentration of solutes.
G. Osmosis
 We use this term to describe the
movement of water or diffusion of
water.
 Water always strives to reach
equilibrium.
 Special terms to describe the
movement of water in/out of cells.
Osmosis
Movement
of Water
Out of Cell
Into Cell
Animal Cell Plant Cell
Crenation
(shrinking)
Cytolysis
(bloating,
bursting)
Plasmolysis
(wilting)
Turgor
Pressure
(crispness, cell
wall prevents
bursting)
Osmosis
 Water will always go to areas of high
concentration to even or dilute the
particles out.
H. Types of Cell Transport
 Cells take in nutrients and expel
waste in the following ways:
 1) Simple diffusion: particles dissolved in
liquid simply diffuse down the concentration gradient.
NO EXTRA ENERGY NEEDED!
Types of Transport
 2) Facilitated Transport: Passive
Transport- particles that are too large are
assisted through the membrane by a
transport protein that creates a doorway.
 No EXTRA ENERGY IS NEEDED!
Types of Transport
 3) Active Transport: particles are
pumped into and out of the cell
AGAINST the concentration gradient by
protein pumps. (Sodium and Potassium
Pumps) (Na+, K+)
 EXTRA ENERGY IS NEEDED! We get this
energy from fat in animals and ATP
molecule in plants. (part of
photosynthesis reaction)
Types of Transport
 4) Pinocytosis: the cell engulfs or expels
a particle of water and stores it in a
vacuole. (Cell Drinking)
 5) Phagocytosis: the cell engulfs a food
particle and forms a food vacuole.
 Example is an Amoeba with its arms that
are called phagocytes. (Cell eating)