1. Consider the two beakers with grapes and soda:
Green grapes – peeled off
Purple grapes – not peeled. J
Describe what you see in words and a drawing.
Try to explain why this happens.
Suggest a way to confirm your explanation.

2. Membrane Structure
Introduction
Membrane structure

3. Properties of Water
H2O
Water Molecules are Polar:

4. Water Molecules are Polar:
Notes
Electrons spend more time around the O than the H.
The “O” side is more negative and “H” side more positive.
The + and – sides attract one another  Water is Sticky!

5. Polar Solute - +
Non-Polar

6. Non-polar substances – Do not mix well with water
(Sugar, Salt, Water colors…)
Notes
Non-polar substances –
Do not mix well with water
(Oils, waxes, Fats)
The same can be said
In other terms..

7. Half hydrophobic, half hydrophilic:
Hydrophilic – “loves” water
Hydrophobic – “hates” water
(or rather – hated by water)
Totally hydrophobic: Oil
Half hydrophobic, half hydrophilic:
phospholipids
Notes
Membrane structure

11. Membrane structure

13. Biological membranes are Non-charged particles
semi-permeable
Pass easily:
Small molecules
Non-charged particles
WATER!
Pass only with help:
Large particles
Ions ?
Notes