Transcript Diffusion and osmosis

DIFFUSION AND OSMOSIS
Types of Cellular Transport

Passive Transport
cell doesn’t use energy
1.
2.
3.

Diffusion
Facilitated Diffusion
Osmosis
Weeee!!
!
high
Active Transport
cell does use energy
1.
2.
3.
Protein Pumps
Endocytosis
Exocytosis
This is
gonna
be hard
work!!
low
high
low
Bacon Frying…
What do you
smell?
Why do you smell
this?
Bacon Frying…
• Fat droplets are released into the air
 steam coming off of the bacon
• Causes the fat droplets (particles) to
collide and disperse.
In science terms…
• DIFFUSION IS OCCURING! 
• The bacon fat droplets (particles)
diffuse from the area of high
concentration (directly above the
frying pan), to areas of low
concentration (the room)
• Continues until equilibrium is reached
Particles equally distributed
throughout the space (room)
Diffusion

Diffusion - Defined as the movement of particles
from areas of high concentration to areas of low
concentration (down the concentration gradient)
 Particles
spread out
 Ex: Solute = perfume Solvent = the air
Low Solute
Concentration
High Solute
Concentration
Diffusion
Diffusion rate (how fast it occurs)
depends on:
 1.
Size- smaller molecules move more easily
 2.
Concentration- high concentration = faster spread

Ex: The more bacon you have (=more fat droplets released),
the faster the smell will spread throughout the room
 3.
Temperature- high temps speed up the process
 Which
will cause the smell to disperse faster?
 Cold bacon in a frying pan and the stove is OFF
OR
 Bacon in a frying pan and the stove in ON
What is a semi-permeable membrane?



A membrane that allows
certain molecules to pass
through it by diffusion or
osmosis
Think about a Ping-Pong
net..
Which would pass through?
Osmosis


Diffusion that involves water.
Movement of water across a semi-permeable
membrane
Cell membranes are semipermeable


Water and some gases move through the membrane
easily, while larger molecules like proteins and
sugars do not.
Cells must regulate- molecules move from internal
environment to external environment (and vice
versa) so that both environments have equal
concentrations.
 Animation:
How Osmosis Works
Osmosis

Diffusion that involves water.
Movement of water across a semi-permeable
membrane
 Water moves from areas of low solute to areas
of high solute

Why do your fingers “shrivel–up” when you are in the water?
Effects of Osmosis on Life


Osmosis- diffusion of water through a
selectively permeable membrane.
There are 3 types of solutions (=Tonicity)
1.) Isotonic
2.) Hypertonic
3.) Hypotonic
Isotonic Solution



WATCH VIDEO OF
BLOOD IN AN
ISOTONIC SOLUTION
Solutions that contain the same concentration of
solutes as the cytoplasm are called isotonic (or
normal saline) solutions.
There is no net movement of water either into or
out of the cell.
Cells maintain their normal shape.
Isotonic Solution
•
Osmosis
Animations for
isotonic,
hypertonic, and
hypotonic solutions
Isotonic The concentration of solutes in the
external solution is equal to the concentration of
solutes inside the cell.
Result Water moves equally in both directions and
the cell remains same size! (Dynamic Equilibrium)
Hypertonic Solution



WATCH VIDEO OF
NORMAL RBCs
SUBJECTED TO A
HYPERTONIC SOLUTION
A hypertonic solution is a solution that
contains more solutes than the cytoplasm of
the cell. (hyper)
Has less water than the cell and
water moves out of the cell.
The cells shrink.
Hypertonic Solution
•
Osmosis
Animations for
isotonic,
hypertonic, and
hypotonic solutions
Hypertonic: The solution has a higher concentration
of solutes and a lower concentration of water than
inside the cell. (High solute; Low water)
shrinks
Result: Water moves from inside the cell into the
solution: Cell shrinks (Plasmolysis/crenation)!
Hypotonic Solution


WATCH VIDEO OF
CRENATED RBCs
SUBJECTED TO A
HYPOTONIC SOLUTION
A hypotonic solution contains less
solute (thus, more water) than the
cytoplasm of the cells.
The water will move into the cells
resulting in the swelling and lysis of
the cells.
Hypotonic Solution
•
Osmosis
Animations for
isotonic,
hypertonic, and
hypotonic solutions
Hypotonic: The solution has a lower concentration
of solutes and a higher concentration of water than
inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside
the cell): Cell Swells and bursts open (cytolysis)!
Let’s take a closer look!
http://www.coolschool.ca/lor/BI12/unit4/
U04L06/rbc.html
What type of solution are these cells in?
A
Hypertonic
B
Isotonic
C
Hypotonic
Tonicity

Used to compare different solutions
 Hypertonic-
higher solute concentration relative to
another
*think hyperactive
 Hypotonic-
lower solute concentration relative to
another
*think hypothermia
 Isotonic-
solutions
equal solute concentrations between two
Cell in Isotonic Solution
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ENVIRONMENT
10% NaCL
90% H2O
CELL
10% NaCL
90% H2O
equilibrium
cell is
at _______________.
WhatThe
is the
direction
of water movement?
NO NET
MOVEMENT
Cell in Hypotonic Solution
24
10% NaCL
90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement??
Cell in Hypertonic Solution
25
15% NaCL
85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?
Cells in Solutions
26
27
Isotonic Solution
NO NET
MOVEMENT OF
H2O (equal amounts
entering & leaving)
Hypotonic
Solution
CYTOLYSIS
Hypertonic
Solution
PLASMOLYSIS
Cytolysis & Plasmolysis
28
Cytolysis
Plasmolysis
Osmosis in Red Blood Cells
29
Isotonic
Hypotonic
Hypertonic
What Happens to Blood Cells?
30