Chapter 19, Problem 19.63P

Interpretation Introduction

Interpretation:

State the difference between diffusion and facilitated diffusion and give examples for each.

Concept Introduction:

The major component of the cell membrane is phospholipids. Phospholipids are amphipathic molecules which means they are both hydrophilic and hydrophobic. They have a hydrophobic core formed from the tails of the fatty acids. The head of phospholipids is hydrophilic. Protein molecules are also present in and on the lipid bilayer are hydrophilic. These molecules allow some molecules to pass through, while act as a barrier for other types of molecules. Therefore, different types of molecules cross the cell membrane in different ways.