Hmmmmm…. If you were stranded in the middle of the

ocean, would you drink the salt water?

Salty Potatoes!1. Grab 3 slices of potatoes and 2 beakers.2. Pour 100mL of water into EACH beaker.3. Pour 2 spoonfuls of salt into ONE beaker4. Place one potato slice into each beaker,

leave one potato slice on a paper towel. 5. 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

1. All cells have a cell membrane

2.Functions:

a.Controls what enters and exits the cell to maintain an internal balance called homeostasis

b.Provides protection and support for the cell

Picture of a real cell membrane.

About Cell Membranes (continued)

3. Structure of cell membrane

Lipid Bilayer -2 layers of phospholipidsa.Phosphate headb.Fatty acid tailsc.Proteins embedded in

membrane

Phospholipid

Lipid Bilayer

About Cell Membranes (continued)

4. Selectively permeable: Allows some molecules in and keeps other molecules out

Pores

Outside of cell

Inside of cell (cytoplasm)

Lipid Bilayer

Proteins

Transport Protein Phospholipids

Sugar chains

Structure of the Cell Membrane

Go to Section:

Membrane movement animation

Polar heads love water

Non-polar tails hide from water.

Fluid Mosaic Model of the

cell membrane

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 LThis 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 Objectives:

1. Identify the characteristics of Passive and Active Transport that the cell membrane uses.

2.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.

HighLow

high

low

Weeee!!!

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 high

low

This is gonna

be hard work!!

Animations of Active Transport & Passive Transport

Types of Active Transport

Proteins embedded in the bilipid layer move molecules from a LOW to HIGH concentration.

Sodium Potassium Pumps

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.

http://bio.winona.edu/berg/Free.htm

Simple Diffusion

Animation

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?

OsmosisObjectives: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.

•Solute (green) too large to move across.

Osmosis animation

Hypotonic Solution

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.

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

Hypertonic Solution

Hypertonic: There is LESS water in the solution than inside the cell.

Result: Water moves out of the cell and the cell shrinks.

• Osmosis Animations for

isotonic, hypertonic, and

hypotonic solutions

shrinks

Isotonic Solution

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 Animations for

isotonic, hypertonic, and

hypotonic solutions

Osmosis in Red Onionhttp://www.teachertube.com/viewVideo.php?video_id=135394

Hypertonic or Hypotonic?

What type of solution are these cells in?

A CB

Hypertonic

Isotonic

Hypotonic