Unit 2 - Lesson 4: Membrane Permeability

What is semi-permeability?

Some things can enter the membrane others can not

What makes up a cell membrane?

Phospholipids

What are the three components of a phospholipid?

A phosphate head group, a glycerol backbone, and two fatty acid tails.

The phospholipid head group is…

Hydrophilic/polar

Fatty acid tails are…

Hydrophobic

What is passive diffusion?

Small, nonpolar molecules can pass through cell membrane

How do small polar molecules (i.e. ethanol) pass through the membrane?

Very slowly. Does NOT want water entering

What else makes up a cell membrane?

Cholesterol

What does cholesterol do?

Inserts itself between phospholipids and maintains fluidity of cell membrane

Third makeup of cell membrane?

Proteins

What do proteins do?

Receptors and transport molecules in and out of cell

What role do glycos play?

Communication, cell recognition