Diffusion
Diffusion
Diffusion is the movement of
molecules from an area of higher
concentration to an area of lower
concentration
Jenny
→ the difference in the
concentration of
molecules across a
space is called the
concentration gradient
Sue & Her Perfume
Diffusion
Equilibrium occurs when the
concentration is the same throughout
a space
Diffusion across a membrane
depends on the size and type of
particle
osmosis
• Osmosis- the diffusion of water
across a selectively permeable
membrane
• Water particles move from an
area of high concentration to an
area of low concentration
• The membrane is only permeable
to water, so only the water moves
• The water moves to try to dilute
the high concentration of solute
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osmosis
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Concept Check
1. How does diffusion differ from osmosis?
2. What does it mean when equilibrium is
reached?
3. Look at the diagram. In which direction
will water flow to reach equilibrium?
Concept Check
1. How does diffusion differ from osmosis?
Diffusion is the movement of substances and osmosis
is the movement of water. Both are from areas of high
concentration to low concentration.
2. What does it mean when equilibrium is
reached? Equilibrium has been reached when all
areas have the same concentration.
3. Look at the diagram.
In which direction
will water flow to
reach equilibrium?
Solution
States
• There are 3 solution states
– Isotonic
– Hypertonic
– Hypotonic
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Isotonic
Solutions
•
Isotonic Solution- the concentration
of dissolved substances outside the
cell is the same as the concentration
of dissolved substances inside the
cell.
→cells retain their normal shape
→cells do not experience osmosis
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Isotonic
Solutions
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Isotonic
Solutions
Hypotonic
Solutions
•
Hypotonic Solution- the concentration of
dissolved substances is lower in the
solution outside the cell than the
concentration inside the cell.
→cells swell from increased osmosis
→water moves into the cell, so internal cell
pressure increases
→the animal cell may burst (cytolysis), but
the cell wall prevents plant cells from
bursting creating turgor pressure
(pressure from water molecules pressing
on the cell wall)
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Hypotonic
Solutions
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Hypotonic
Solutions
hypertonic
Solutions
• Hypertonic Solution- the
concentration of dissolved
substances outside the cell is
higher than the concentration
inside the cell.
→cells shrink form increased
osmosis out of the cell
(plasmolysis or crenation)
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hypertonic
Solutions
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hypertonic
Solutions
Solutions
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Solutions
Concept Check
Each of the cells below have experienced a different solution state.
Label what type of solution state each cell has experienced.
Hypotonic
Isotonic
Hypertonic
Passive
Transport
• Passive Transport- movement of particles
across membranes by diffusion.
→ the cell uses NO ENERGY
→ Examples: water, lipids, and lipid
soluble substances
• Facilitated Diffusion- passive transport of
materials with the aid of carrier proteins
(channel). (A form of passive transport.)
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Passive
Transport
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Passive
Transport
Concept Check
1. What is the difference between facilitated
diffusion and simple diffusion?
2. What do facilitated diffusion, simple diffusion
and osmosis have in common?
3. Why are facilitated diffusion, simple diffusion
and osmosis considered passive transport
mechanisms?
Concept Check
1. What is the difference between facilitated
diffusion and simple diffusion?
Simple
diffusion does not require a channel or carrier protein. The
molecules are small enough to pass through the membrane.
Facilitated diffusion transports large molecules and requires a
carrier or channel protein of some type. Both move substances
from areas of high concentration to areas of low concentration.
2. What do facilitated diffusion, simple diffusion
and osmosis have in common? They all move
substances from areas of high concentration to areas of low
concentration. None of the mechanisms require energy.
3. Why are facilitated diffusion, simple diffusion
and osmosis considered passive transport
mechanisms? No Energy Needed
ACTIVE
Transport
• Active Transport- REQUIRES ENERGYmovement of particles from a region of
lower concentration to a region of
higher concentration Ex: proton
pumps
→ uses transport proteins
• a specific molecule binds to the
protein
• the protein changes shape so the
molecule is moved and released on the
inside of the membrane
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ACTIVE
Transport
ACTIVE
Transport
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ACTIVE
Transport
Endocytosis- a process by which a cell
surrounds and takes in material from
its environment. (2 types)
→Pinocytosis- the taking in of liquid
material
→Phagocytosis- the taking in of solids
Exocytosis- the expulsion or secretion of
materials from the cell
→ wastes or cell products
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ACTIVE
Transport
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ACTIVE
Transport
Concept Check
1. Describe two ways active transport differs from
passive transport.
2. Name the form active transport that engulfs
solid materials from the extracellular space.
3. What type of active transport is shown in the diagram?
Concept Check
1. Describe two ways active transport differs from
passive transport.
A. Active transport requires energy, passive transport does not
require energy.
B. Active transport moves material against their gradients, passive
moves material with their gradients.
2. Name the form active transport that engulfs
solid materials from the extracellular space.
Phagocytosis
3. What type of active transport is shown in the diagram?
Pinocytosis
ACTIVE &
Passive
Transport