Chapter 5, Problem 12SQ

Summary Introduction

Introduction: Metabolic pathways require the participation of molecules that must move across membranes and through cells. Plasma membrane is composed of lipid bilayer. It is non-polar in nature. Large polar molecules and ions cannot move through the lipid bilayer, but nonpolar molecules can and small polar molecules can move through it by diffusion. For large polar molecules and ions, there are special proteins called transport proteins that cross through the lipid bilayer.