MembranesPhospholipids and Bilayers

What do cell membranes consist of?

Experiment:A B C D E F

10 cc of milk

10 cc of vinegar

10 cc of oil

10 cc of vinegar

piece of red cabbage

10 cc of vinegar

10 cc of milk

10 cc of water

5 drops of washing up liquid

10 cc of oil

10 cc of water

5 drops of washing up liquid

piece of red cabbage

10 cc of water

5 drops of washing up liquid

results:

milk clotted

results:

oil floats on top

results:

bright pink colour leaks out

results:

milk emulsified (little droplets)

results:

oil emulsified

(little droplets)

results:

violet colour leaks out

Conclusions: Cell membranes consist of proteins and fats (lipids)

Lipid packing

Arrangements of lipids in aqueous media

Hydrophobic surfaces such as fatty acid chains aggregate in aqueous solutions, caused by aversion of water molecules to hydrophobic surfaces which force the water into ordered structures. Alternative structures with the hydrophobic surfaces as compact as possible are favoured.

Membrane fluidity: Frye-Edidin experiment

Membrane fluidity: Frye-Edidin experiment

Frye-Edidin experiment

Frye-Edidin experiment