How Does the Cell Membrane Control What Enters and Leaves?

💡 The Answer

• The hydrophobic core selectively allows small nonpolar molecules to diffuse freely across the membrane.
• Polar molecules and ions require specific transport proteins like channels and carriers to cross.
• Active transport pumps use ATP to move substances against their concentration gradient.
• Endocytosis and exocytosis enable the uptake and release of large particles or macromolecules.