Download Properties of Water

PASSIVE TRANSPORT
A.K.A. THE LAZY ONE THAT DOESN’T NEED ENERGY
Przeworski
HOMEOSTASIS
• https://www.youtube.com/watch?v=9RLnlXNlfdk
• Why do we want to keep a constant internal
environment?
• Temperature
• pH
• Salt/Potassium/Ion content
In passive transport:
oMolecules always move across the cell membrane
without the use of energy
oMolecules always move from high to low
concentration (from where there are more to where
there are fewer)
Low
High
High
Low
ATP
Diffusion
oDiffusion is the most basic form of passive transport
o Occurs everywhere, not just across membranes
oEquilibrium is reached when diffusion has caused molecules to
spread out evenly
Facilitated Diffusion
In facilitated diffusion, molecules move through the
membrane with help from proteins
o Channel proteins are open doors
o Carrier proteins open and close
Osmosis
In Osmosis, water molecules diffuse through a
membrane
oSolute: a substance dissolved in a liquid
oSolvent: liquid that dissolves the solute
oSolution: mixture of solute and solvent
Osmosis
Tonicity describes relative concentrations of solute:
o Hypertonic: Concentration is higher relative to something else
o Hypotonic: Concentration is lower relative to something else
o Isotonic: Both concentrations are equal
In which beaker would we expect to see the
greatest movement of particles? (list the
percents as your answer)
Cell in Hypertonic Solution
15% Solute
85% H2O
CELL
5% Solute
95% H2O
WHICH DIRECTION WILL THE WATER
MOVE?
Cell in Hypotonic Solution
20% Solute
80% H2O
CELL
30% Solute
70% H2O
WHICH DIRECTION WILL THE WATER
MOVE?
Cell in Isotonic Solution
10% Solute
90% H2O
CELL
10% Solute
90% H2O
WHICH DIRECTION WILL THE WATER
MOVE?
What happens when plant cells are placed in
solutions of different tonicity?
?
?
• Plasmolyzed: Water leaves plant cells, causes the cell
membrane to pull away from the cell wall (plasmolysis),
plant wilts
• Turgid: Water moves into plant cells, makes cells plump,
plant remains rigid
VIDEO-BIO
• https://www.youtube.com/watch?v=IaZ8MtF3C6M
• Video: Pre-AP (first 5 minutes)
• https://www.youtube.com/watch?v=dPKvHrD1eS4
EXIT TICKET:
A student measures the mass of each of six potato cores
and places one core in each of six different unknown
solutions. After a period of time, the student removes the
potato cores and measures the mass of each one.
Solution
1
2
3
4
5
6
Potato Core Mass
Increase
Decrease
No Change
No Change
Decrease
Increase
Which two
potato cores
were placed
in an isotonic
solution?