Cell Membranes are composed of 2 Layers of Phospholipids = Phospholipid Bilayer

• 2 layers of phospholipids• Heads = love water• Tails = hate water• Middle = oily

substance that keeps water out

Soap + Oil

The cell membrane is semi-permeable: allows substances to pass based on size

DEMO!

What enters and exits cells?

• Water Small molecules can pass through the phospholipid bilayer; but how

do the big molecules get into

cells?

•Oxygen

•Carbon Dioxide

•Glucose

http://www.teachersdomain.org/asset/tdc02_int_membraneweb/

•Enzymes

The Fluid Mosaic Model of The Cell Membrane

• Fluid: moves easily• Mosaic: made of phospholipids,

carbohydrates, protein channels

Cell Transport Jigsaw:• Each group will read about a

different type of cell transport• You are to become an

EXPERT in your topic.

• While reading:• Pull out vocab words and

define. • Take notes on important info.• Summarize the transport

type.

• You will then switch groups and become the teacher of that topic in your group.• You are fully responsible for

the people in your group learning your section of notes.

• Group 1: Diffusion

• Group 2: Osmosis

• Group 3: Facilitated Diffusion/Ion Channels

• Group 4: Sodium Pumps

• Group 5: Exo/Endocytosis

• **B2 Only:• Group 5:Exocytosis• Group 6: Endocytosis

Cell Transport

Passive Transport Active Transport

Terms given for the movement of molecules into and out of the cell:

Passive Transport: No Energy Required• Simple Diffusion• Osmosis• Facilitated Diffusion

Active Transport: Energy (ATP) Required• Cell Membrane Pumps• Endocytosis• Exocytosis

Passive Transport: Simple Diffusion

Movement of particles from

HIGH CONCENTRATION LOW CONCENTRATION

until EQUILIBRIUM is reached. (what is equilibrium?)

Demos: Food Coloring and Perfume

What will happen?

The molecules continue to move from areas of high concentration to low concentration until

EQUILIBRIUM is reached!

= oxygen

Simple Diffusion in Cells: Oxygen and Carbon Dioxide

Passive Transport: Facilitated Diffusion

• Diffusion of molecules that are too large• Need the help of protein channels• Example: Glucose

Passive Transport: OsmosisMovement of WATER from

HIGH CONCENTRATION LOW CONCENTRATION (through a protein channel)

until EQUILIBRIUM is reached

* osmosis = facilitated diffusion of water because of oily center of cell membrane

What will happen? = water

Higher concentration of

solute inside the cell than outside the cell

Lower concentration of solute inside the

cell than outside the cell

Equal concentration of solute inside and

outside the cell

= solute

Why does the water move,

not the molecules in

osmosis?

Switching from Passive Transport to Active Transport.

What do you think the difference will be?

Active Transport: Cell Membrane Pumps

• The movement of particles from low to high concentration with the help of a protein pump. Requires Energy (ATP)!

Active Transport: Exocytosis• EXO = OUT!• How cells release materials (proteins, wastes, toxins)

Active Transport: Endocytosis• ENDO = IN!• How large molecules enter the cell