Unit 3: The Cell
Chapter 7:
Cell Structure and Function
and Function
7-3
7-3: Cell Transport
A)
Passive Transport
1.
Diffusion
2.
Facilitated
Diffusion
3.
Osmosis
B) Active Transport
1.
Molecular
Transport
2.
Bulk Transport
!
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A -1
•
•
A) Passive Transport
The movement of materials across the cell membrane
without using cellular energy is called passive transport.
Every living cell exists in a liquid environment.
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A -2
A) Passive Transport
1) Diffusion
•
•
Particles tend to move from
an area where they are more
concentrated to an area
where they are less
concentrated.
Particles moving from an
area of high concentration to
an area of lower
concentration is known as
diffusion.
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A) Passive Transport
1) Diffusion
A)
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A) Passive Transport
1) Diffusion
B)
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A) Passive Transport
1) Diffusion
C)
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A) Passive Transport
2) Facilitated Diffusion
•
Facilitated diffusion Molecules that cannot cross the
membrane pass through special protein channels
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A) Passive Transport
2) Facilitated Diffusion
•
Proteins act as carriers, or channels, making it easy for
certain molecules to cross.
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A) Passive Transport
3) Osmosis
•
•
Osmosis is the diffusion of
water through a selectively
permeable membrane.
Osmosis is the movement of
water molecules from an area
of higher concentration to an
area of lower concentration.
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http://www.youtube.com/watch?v=w3_8FSrqc-I
A) Passive Transport
3) Osmosis
How it Works 1
This barrier is permeable to
water but not to sugar.
The concentration of water is
lower on the right, where
more of the solution is made
of sugar.
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A) Passive Transport
3) Osmosis
How it Works 2
concentrated sugar solution on
the right is hypertonic, or
“above strength,”
The dilute sugar solution on
the left is hypotonic, or “below
strength.”
•
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A) Passive Transport
3) Osmosis
How it Works 3
The concentration (RATIO) will
become equal, even if the
level of water will not be.
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A) Passive Transport
3) Osmosis
Osmotic Pressure
•
•
For organisms to survive, they must have a balanced intake
and loss of water.
The net movement of
water out of or into a cell
exerts a force known as
osmotic pressure.
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A) Passive Transport
3) Osmosis
Osmotic Pressure
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A) Passive Transport
3) Osmosis
Osmotic Pressure
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•
B) Active Transport
Active transport requires energy. The movement of
material from low concentration to high concentration.
•
Like rolling a ball up a hill
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B) Active Transport
1) Molecular Transport
•
Small molecules are
carried across
membrane by protein
pumps that use
energy
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B) Active Transport
2) Bulk
Transport
•
Endocytosis - the
cell membrane folds
over a particle and
takes it into the
cytoplasm
!
•
The cell eats
something
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B) Active Transport
2) Bulk
Transport
•
Exocytosis - the
membrane of a vacuole
fuses with the cell
membrane, forcing the
contents out of the cell.
!
•
The cell spits out
something
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B -5
•
B) Active Transport
Exocytosis - the
membrane of a
vacuole fuses
with the cell
membrane,
forcing the
contents out of
the cell.
!
•
The cell spits out
something
2) Bulk
Transport