Hmmmmm….

If you were stranded in the middle of the ocean, would
you drink the salt water?
Salty Potatoes!
1.
2.
3.
4.
5.
Grab 3 slices of potatoes and 2 beakers.
Pour 100mL of water into EACH beaker.
Pour 2 spoonfuls of salt into ONE beaker
Place one potato slice into each beaker, leave one
potato slice on a paper towel.
In your journal, predict what will happen to the size and
texture of the potato at the end of class.
The Cell Membrane &
Transportation of Molecules
Objectives:
1.
To describe the role and structure of the cell membrane.
2.
Predict how molecules will enter and leave the cell.
About Cell Membranes
All cells have a cell membrane
2. Functions:
1.
Controls what enters and
exits the cell to maintain
an internal balance called
homeostasis
b. Provides protection and
support for the cell
a.
Picture of a real cell
membrane.
About Cell Membranes (continued)
3.
Structure of cell membrane
Lipid Bilayer -2 layers of
phospholipids
Phosphate head
b. Fatty acid tails
c. Proteins embedded in
membrane
a.
Phospholipid
Lipid Bilayer
About Cell Membranes (continued)

4. Selectively permeable: Allows some molecules in and
keeps other molecules out
Pores
Structure of the Cell Membrane
Outside of cell
Sugar chains
Proteins
Lipid
Bilayer
Transport
Protein
Phospholipids
Inside of cell
(cytoplasm)
Go to
Section:
Polar heads
love water
Non-polar
tails hide
from water.
Fluid Mosaic
Model of the
cell membrane
Membrane
movement
animation
Hmmmmm….

If you were stranded in the middle of the ocean, would
you drink the salt water?
Reflection

In your journals make a chart and fill in:
O
W
L
This is what I
OBSERVED
That is what I
WONDER
This is what I
LEARNED
Hmmmmm….

If you were stranded in the middle of the ocean, would
you drink the salt water?
Video



www.brainpop.com
“Passive Transport”
“Gills”
Passive vs Active Transport

1.
2.
Objectives:
Identify the characteristics of Passive and Active
Transport that the cell membrane uses.
Set up a lab and observe an example of passive
transport.
Passive Transport




cell uses no energy
molecules move randomly
Molecules spread out from an area of high
concentration to an area of low concentration.
HighLow
Weeee!!!
high
low
Active Transport
•cell uses energy
•actively moves molecules to where they are needed
•Movement from an area of low concentration
to an area of high concentration
•Low  High
This is
gonna be
hard
work!!
high
Animations of Active Transport & Passive
Transport
low
Types of Active Transport
Sodium Potassium Pumps
Proteins embedded in
the bilipid layer move
molecules from a LOW
to HIGH concentration.
Passive Transport:
1.
Diffusion: random movement of
particles from high

to low
Diffusion continues until all
molecules are evenly spaced
(equilibrium is reached)-Note:
molecules will still move around but
stay spread out.
Simple Diffusion
Animation
http://bio.winona.edu/berg/Free.htm
Diffusion & Dialysis Tube Lab

It is very difficult to measure or see diffusion actually occurring in cells
because of the small size of most cells. Dialysis tubing is a manmade
semi-permeable membrane that is used to treat people who have kidney
failure. It acts similarly to a real plasma membrane.The driving force
behind dialysis is the concentration difference between two solutions on
opposite sides of the membrane.

Which molecule will diffuse across the semi-permeable membrane?
Iodine or Starch?
Osmosis
Objectives:
1. Collect results from yesterday’s lab and conclude
whether iodine or starch diffused through the membrane.
2. Explain the process of osmosis and describe the three
ways it can affect the size of a cell.
Diffusion & Dialysis Tube Lab Results

2. Osmosis: diffusion of water

Water moves from high to low
concentrations
•Water moves freely
through pores.
Osmosis animation
•Solute (green) too large
to move across.
Hypotonic Solution
•
Osmosis Animations
for isotonic,
hypertonic, and
hypotonic solutions
Hypotonic: There is MORE water in the solution than inside
the cell.
Result:Water moves from the solution to inside the cell.
Animals cells swell and burst, plants cell swell up and do
not burst.
Hypertonic Solution
•
Osmosis Animations
for isotonic,
hypertonic, and
hypotonic solutions
Hypertonic: There is LESS water in the solution than inside
the cell.
shrinks
Result:Water moves out of the cell and the cell shrinks.
•
Isotonic Solution
Osmosis Animations
for isotonic,
hypertonic, and
hypotonic solutions
Isotonic: The concentration of water is equal inside and
outside the cell. (Equilibrium  homeostasis)
Result: Water moves equally in both directions and the cell
remains same size!
Osmosis in Red Onion
http://www.teachertube.com/viewVideo.php?video_id=135394
Hypertonic or Hypotonic?
What type of solution are these cells in?
A
B
C
Hypertonic
Isotonic
Hypotonic