TONICITY

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TONICITY
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Vocabulary Terms

• Solution
• A liquid (usually water) and its dissolved solutes

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Vocabulary Terms

• Solution
• A liquid (usually water) and its dissolved
  solutes
• Solute
• A substance that is dissolved in a liquid

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Vocabulary Terms

• Solution
• A liquid (usually water) and its dissolved
  solutes
• Solute
• A substance that is dissolved in a liquid
• Solvent
• A liquid that has dissolved (or can dissolve) one
  or more solutes

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Vocabulary Terms

• Solution
• A liquid (usually water) and its dissolved
  solutes
• Solute
• A substance that is dissolved in a liquid
• Solvent
• A liquid that has dissolved (or can dissolve) one
  or more solutes
• Osmosis
• The diffusion of water across a membrane. In
  osmosis, water diffuses from regions of higher
  water concentration to regions of lower water
  concentration.

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Vocabulary Terms

• Tonicity
• The relationship between two environments
  (usually a cell and a solution surrounding it).

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Vocabulary Terms

• Tonicity
• The relationship between two environments
  (usually a cell and a solution surrounding it).
• Hypertonic Having a greater solute
  concentration than that which it is being
  compared with

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Vocabulary Terms

• Tonicity
• The relationship between two environments
  (usually a cell and a solution surrounding it).
• Hypertonic Having a greater solute
  concentration than that which it is being
  compared with
• Hypotonic Having a lower solute concentration
  than that which it is being compared with

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Vocabulary Terms

• Tonicity
• The relationship between two environments
  (usually a cell and a solution surrounding it).
• Hypertonic Having a greater solute
  concentration than that which it is being
  compared with
• Hypotonic Having a lower solute concentration
  than that which it is being compared with
• Isotonic Having the same solute concentration
  as the solution with which it is being compared.

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BIOFACT

• In hypotonic solutions, cells tend to take up
  water, while in hypertonic solutions, cells tend
  to lose water. Animal cells must remain isotonic
  with respect to the environment in order to
  prevent destructive gain or loss of water.

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BIOFACT

• Plant cells have cell walls which prevent the
  cells from bursting under hypotonic conditions.
  The turgor pressure that develops under these
  conditions keeps plants upright and stretches the
  cell wall during cell growth.

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The three following photos illustrate plasmolysis
by onion epidermal cells. Their vacuoles contain
anthocyaninis which provide a uniform appearance
for "Turgid" cells. The vacuoles of these cells
have a positive turgor pressure and press the
cytoplasm against the cell wall.
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When these cells are placed in a salt solution,
water will leave the cells because they have a
greater water potential compared to the salt
solution. If the water potential of the salt
solution is extremely low water will continue to
leave the cells and the Protoplast will shrink.
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In extreme cases the plasmalemma will become
detached from the Cell Wall. This severs
plasmodesmatal connections between cells and can
be fatal.
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CRENATION
HUMAN RED BLOOD CELL In 4 Salt Solution
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HEMOLYSIS
HUMAN RED BLOOD CELL In Distilled Water
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PROBLEMS

• ASK

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PROBLEMS

• ASK
• 1. Is solution A hypertonic, hypotonic or
  isotonic to solution B in the dialysis bag?

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PROBLEMS

• ASK
• 1. Is solution A hypertonic, hypotonic or
  isotonic to solution B in the dialysis bag?
• 2. What are the movements of water between the
  two compartments?

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PROBLEMS

• ASK
• 1. Is solution A hypertonic, hypotonic or
  isotonic to solution B in the dialysis bag?
• 2. What are the movements of water between the
  two compartments?
• 3. What is the effect of solution A on the shape
  of the dialysis bag?

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PROBLEMS

• ASK
• 1. Is solution A hypertonic, hypotonic or
  isotonic to solution B in the dialysis bag?
• 2. What are the movements of water between the
  two compartments?
• 3. What is the effect of solution A on the shape
  of the dialysis bag?
• These three questions are identical!

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To predict what is happening you have to
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To predict what is happening you have to
1. Identify all the different type of solute
particles in all the compartments of the system
(Na glucose Cl-, etc...)
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To predict what is happening you have to
1. Identify all the different type of solute
particles in all the compartments of the system
(Na glucose Cl-, etc...) 2. Figure out what
each type of solute particles "want to do". Can
they do it or not?
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To predict what is happening you have to
1. Identify all the different type of solute
particles in all the compartments of the system
(Na glucose Cl-, etc...) 2. Figure out what
each type of solute particles "want to do". Can
they do it or not? Each type of solute particles
want to move along its gradient of Potential
Energy until equilibrium is reached (equilibrium
means that its Potential Energy is the same in
all the compartment).
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To predict what is happening you have to
1. Identify all the different type of solute
particles in all the compartments of the system
(Na glucose Cl-, etc...) 2. Figure out what
each type of solute particles "want to do". Can
they do it or not? Each type of solute particles
want to move along its gradient of Potential
Energy until equilibrium is reached (equilibrium
means that its Potential Energy is the same in
all the compartment). Can they do it or not? They
can go from one compartment to another only if
they are penetrating solute particles.
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To predict what is happening you have to
1. Identify all the different type of solute
particles in all the compartments of the system
(Na glucose Cl-, etc...) 2. Figure out what
each type of solute particles "want to do". Can
they do it or not? Each type of solute particles
want to move along its gradient of Potential
Energy until equilibrium is reached (equilibrium
means that its Potential Energy is the same in
all the compartment). Can they do it or not? They
can go from one compartment to another only if
they are penetrating solute particles. 3. Make
them do it.
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To predict what is happening you have to
4. THEN, figure out the overall concentration of
all the solute particles (or osmolarity) in each
compartments
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To predict what is happening you have to
4. THEN, figure out the overall concentration of
all the solute particles (or osmolarity) in each
compartments 5. Water also moves along its
gradient of potential energy. Now that you know
the osmolarity of the solutions and provided that
all the other variables affecting potential
energy of water (pressure, temperature etc..) are
identical in all the compartments you can predict
the movement of water.
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To predict what is happening you have to
4. THEN, figure out the overall concentration of
all the solute particles (or osmolarity) in each
compartments 5. Water also moves along its
gradient of potential energy. Now that you know
the osmolarity of the solutions and provided that
all the other variables affecting potential
energy of water (pressure, temperature etc..) are
identical in all the compartments you can predict
the movement of water. 6. Now that you know how
water moves, figure out how the shape of the
dialysis bag will be affected.
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BIO QUESTION
Solution A is hypotonic to solution B. The
particles cannot penetrate the membrane. Will the
dialysis bag change shape?
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BIO QUESTION
Solution A is hypotonic to solution B. The solute
particles are non-penetrating. Will the dialysis
bag change shape?
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FOOD FOR THOUGHT