PATHOLOGY

Detailed explanation-1: -A cell membrane controls what goes in and out of the cell. Because of the hydrophilic and hydrophobic regions of the phospholipid bilayer, small nonpolar molecules cross the membrane easily, while large and hydrophilic molecules cannot cross easily.

Detailed explanation-2: -Cell Membrane (Plasma Membrane) The cell membrane consists of a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials entering and exiting the cell.

Detailed explanation-3: -Specialized proteins in the cell membrane regulate the concentration of specific molecules inside the cell. Membrane transport proteins are specific and selective for the molecules they move, and they often use energy to catalyze passage.

Detailed explanation-4: -Nutrients, such as sugars or amino acids, must enter the cell, and certain products of metabolism must leave the cell. Such molecules diffuse passively through protein channels in facilitated diffusion or are pumped across the membrane by transmembrane transporters.