Download Hypotonic

Homeostasis requires
exchanging materials
with the environment.
How do you do it?
Surfaces of contact with the
environment let in oxygen and
nutrients and excrete wastes.
The surface of contact between a cell and
its environment is its plasma membrane.
Fluid Mosaic Model
(description of membrane)
Outside cell
Inside cell
Cell/Plasma Membrane
Fluid Mosaic Model
• The cell, or plasma membrane is made of
hydrophobic molecules called phospholipids.
• Proteins located in the membrane can
flow/move and perform many functions,
including receiving stimuli from the
environment and transporting substances in
and out of cell.
↓
The plasma membrane is
semi-permeable / selectively permeable:
it controls what goes in/out of cell
Cell Membrane Diagram
(add details as you go)
Phospholipid bilayer
Outside cell
Inside cell
Phospholipid Bilayer
Outside of Cell
Hydrophilic
Phosphate Heads
Hydrophobic
Tails
Saturated or
Unsaturated?
Inside of Cell
Cell Transport 
movement of substances in and out of cell,
needed to maintain homeostasis
What substances does a cell need to move in and out?
Water moves freely through aquaporins.
O2 and CO2 move freely through membrane.
Polar particles need specialized carrier proteins:
ions, glucose
Media Links For Lecture\08-02-MembraneStructure.mov
Passive Transport
Does not require the use of energy from ATP.
(uses the kinetic energy in matter/stuff moving in/out)
Diffusion – Spreading of matter from one area to another.
Matter always diffuses from areas of higher concentration to areas
of lower concentration  EQUILIBRIUM (same concentration
everywhere)
Diffusion is “free” because stuff moves
down/with a concentration gradient.
Ex.: food coloring spreading/mixing in
water;
H2O, O2, CO2, monomer nutrients (some)
moving in/out of cell
Movie Time
Cell Membrane & Passive Transport
Mrs. Nordstrom:
*press esc key (leave presentation mode),
then double click below*
08-10-Diffusion.mov
08-02-MembraneStructure.mov
Osmosis – Diffusion of water through a semi-permeable
membrane.
Water flows from areas of lower solute concentration (+ water)
to areas of higher solute concentration (- water).
Osmosis - Solution Concentration & Effect on Cells
(show cells in a solution & net movement of water)
Hypertonic
Isotonic
Hypotonic
Very Hypotonic
Hypertonic Solution
(Hypotonic Cell)
Is there a concentration gradient?
Plasmolysis
Cell shrinks
(loses water)
Isotonic Solution
(Isotonic Cell)
Is there a concentration gradient?
Equilibrium
Happy cell 
Hypotonic Solution
(Hypertonic Cell)
Is there a concentration gradient?
H2O
Cell swells
(gains water)
Very Hypotonic Solution
H 2O
Cell swells
(gains water)
Cytolysis
Cell lysis 
•Movie Time *
Osmosis OR
The Movement of Water Through a Semi-Permeable Membrane
Mrs. Nordstrom:
*press esc key (leave presentation mode),
then double click below*
08-11-Osmosis.mov
Facilitated Diffusion – requires the use of a carrier protein on
the cell membrane (still no ATP energy needed).
Ex.: glucose molecules, ions – why? Polarity…
Protein channels are specific for the particles they move.
Carrier Protein / Ion Channel
Glucose always use F.D.
Ions use F.D.
Movie Time 
Facilitated Diffusion Illustration
At Colorado State Univ. Web Page
Turgid or Flaccid??
(Macroscopic Term)
Salt Water
Hypertonic
Turgid or Flaccid??
(Macroscopic Term)
Tap Water
Hypotonic
A
B
C
Prefix refers to the amount of Dissolved Solute
(stuff)
Hypertonic - Excess ‘stuff’........
Hypotonic - Less ‘stuff’……….
Isotonic –
Equal ‘stuff’…………
Osmosis Practice
Can you predict what will happen?
Think of water and solute
concentrations.
Cell’s
Environment is
Cell is 95% Water
90% water
Water Pushes Out
Osmosis
Cell is 95% Water
Cell’s
Environment is
100% water
Water Pushes into Cell
Osmosis
Cell is 95% Water
Cell’s
Environment is
95% water
Osmosis
Cell’s Environment
is 90% water
Cell is 95% Water
Hypotonic
The Cell is ___________
Hypertonic
The Cell’s environment is____________
The Future Fate of the Cell might be to
PLASMOLYZE
Osmosis Cell’s Environment is 100% water
Cell is 95% Water
Hypertonic
The Cell is ___________
Hypotonic
The Cell’s environment is____________
The Fate of the Cell is Cytolysis
Osmosis
Cell is 95% Water
Cell’s Environment is 95% water
The Cell’s environment is____________
The Cell is ________________________
The Cell is at Equilibrium
Cycl
osis
Plas
moly
sis
Which is more Plasmolyzed?
Which might be further in the
process of re-hydrating?
Normal Plant Cell
Isotonic Cell
Isotonic Environment
Hypertonic Env.
Plasmolysis
Hypotonic Cell
Hypotonic Env.
Cytolysis
Hypertonic Cell
RBC in Isotonic Environment
The cell is also Isotonic
Plasmolysis
Cell is Hypotonic,
Env. is Hypertonic
Cytolysis
Cell is Hypertonic,
Env. Is Hypotonic
A
B
C
Simple Diffusion
Movement of ‘stuff’ down the Concentration
Gradient through a semi-permeable cell
membrane by Kinetic Energy
Media Links For Lecture\08-10-Diffusion.mov
Passive Transport
1. Osmosis
Movement of water in / out of cell
2. Diffusion
Movement of H2O, O2, CO2, Urea, monomer
nutrients: either in / out of cell
3. Facilitated Diffusion - Glucose
Movement of Glucose (C6H12O6) into the cell.
Helped by a specific Integrated Protein
4. Ion Channels
Movement of ions in / out of cell, must go
through specific integrated proteins