1. Cell Membrane bubble lab
Honors Biology I

2. Interface between internal & external cell environment
CELL MEMBRANES
Interface between internal & external cell environment
Controls what enters and exits the cell to maintain an internal balance called homeostasis
Needed materials IN (i.e. glucose)
Waste materials OUT (i.e. CO2)
Provides protection and support for the cell

3. A Bubble is a lot like a cell membrane
Phospholipids (a major cell membrane component) have a love-hate relationship with water.
Head = attracted to water
Tail = repelled by water
SOAP MOLECULE has the same SPLIT PERSONALITY!

4. The hydrocarbon tail of soap mixes with & dissolves in other hydrocarbons (i.e. oils and fats).
The head region grabs onto passing H2O molecules rinsing down the drain.
Bubbles have 3 layers: middle = a thin film of water, inner & outer = soap molecule layers with hydrophilic heads facing water (toward the center) and hydrophobic tails pointing out

5. How Soap Works
The hydrophobic tails of soap molecules embed in grease and oil, breaking it up into particles called micelles that lift off the surface and disperse into water.
“Like dissolves like.”
Non-polar, hydrophobic tails are LIPOPHILIC (“oil-loving”) & will embed in grease and oils that help dirt/stains adhere to surfaces. HYDROPHILIC heads remain in contact with water.
Soap is an emulsifier, or it allows a compound that is usually insoluble in water to dissolve

6. MICELLES
Aggregates of surfactant molecules, micelles have hydrophilic heads in contact with surrounding water (solvent), packing the hydrophobic tails in the center.

7. Questions?