This document discusses how cells transport materials across their selectively permeable membranes. It describes three main types of transport: passive transport which includes diffusion and osmosis and moves substances down concentration gradients without energy; facilitated diffusion which uses transport proteins to move larger molecules; and active transport which moves substances against concentration gradients using energy from ATP with the help of transport proteins. Endocytosis and exocytosis are also covered as forms of active transport where large particles enter or leave cells through membrane invagination and budding.

1. Chapter 3
Cell Processes
Section 2: Moving Cellular
Material
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2. II. Moving Cellular Material
A. Selectively Permeable Membrane
1. Cells take in food, oxygen, and other
substances; they also release waste and
Carbon Dioxide CO2.
2. These materials enter and leave through the
cell membrane; acts like a screen.
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3. II. Moving Cellular Material
3. Selectively Permeable: ability for a
substance to allow certain things to pass
through and keep other things out.
a. This occurs by the size of the openings in the cell
membrane.
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4. II. Moving Cellular Material
B. Passive Transport
1. The movement of substances through the
cell membrane WITHOUT the use of energy
(ATP).
2. Three types of passive transport
a. Diffusion
b. Osmosis
c. Facilitated Diffusion
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5. II. Moving Cellular Material
C. What is Diffusion? (Passive Transport)
1. Diffusion: random movement of molecules from
an area of high concentration to an area of low
concentration. (Crowded to Uncrowded)
a. Example: Spraying perfume, adding a drop of food
coloring into water.
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6. DIFFUSION
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7. DIFFUSION
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8. II. Moving Cellular Material
D. What is Equilibrium?
1. When the same number of molecules are on
both sides of a membrane.
a. All cells want this but it rarely happens.
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9. EQUILIBRIUM
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10. II. Moving Cellular Material
E. Osmosis (Passive Transport)
1. Osmosis is the diffusion of water and only
water across a membrane without the use of
energy (ATP).
a. Water goes from high concentration to low
concentration in diffusion.
b. Crowded to less crowded.
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11. II. Moving Cellular Material
E. Osmosis (Passive Transport)
1. Osmosis is the diffusion of water and only
water across a membrane without the use of
energy.
a. Water goes from high concentration to low
concentration in diffusion.
b. Crowded to less crowded.
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12. II. Moving Cellular Material
F. Cells and Water
1. If a cell is placed into a container of pure water it
would keep sucking in the water and would not
stop.
a. This will eventually cause the cell to swell to a point of
exploding.
2. If a cell is placed in salt water, the cell would get
rid of all its water; trying to dilute the salt outside
the cell.
a. This would cause the cell to shrivel up and die.
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13. http://www.biologycorner.com/resources/hypertonic.gif
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14. http://www.biologycorner.com/resources/hypotonic.gif
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15. http://www.biologycorner.com/resources/isotonic.gif
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16. Cells and Water
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17. Label: Hypo, Hyper, or Iso!!
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18. II. Moving Cellular Material
G. Facilitated Diffusion
(Passive Trasnport)
1. When LARGE
materials need to get
into a cell l; from high
to low; proteins called
TRANSPORT
PROTEINS are used to
help in this process.
a. Example: Plant roots
taking in material for the
plant.
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19. http://w3.uokhsc.edu/human_physiology/presentation/facildiffani.gif 19

20. II. Moving Cellular Material
H. Active Transport
1. If energy is needed to get something into or out
of a cell ACTIVE TRANSPORT takes place.
2. Active transport is the movement of molecules
from an area of low concentration to an area of
high concentration with the use of energy (ATP).
a. Cells do not like to do this but it is necessary at times.
b. Transport proteins are needed to do this.
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21. 21

22. http://www.sp.uconn.edu/~terry/images/anim/antiport.gif
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23. II. Moving Cellular Material
I. What is Endocytosis? (Active Transport)
1. The process of taking in large substances by
surrounding them with the membrane and
enclosing them.
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24. II. Moving Cellular Material
J. Two types of Endocytosis
1. Phagocytosis: large SOLIDS entering the
membrane.
a. Amoebas eat this way.
b. White blood cells surround germs this way.
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25. http://www.biologie.uni-hamburg.de/b-online/library/biology107/bi107vc/fa99/terry/images/PhagoAnA.gif
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26. II. Moving Cellular Material
J. Two types of Endocytosis
2. Pinocytosis: Large liquids entering a membrane.
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27. II. Moving Cellular Material
K. Exocytosis (Active Transport)
1. The releasing of wastes outside the cell.
a. This process is the opposite of endocytosis.
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