Cell Membrane Transport Mechanisms

📋 Course Outline

1. Lipid Bilayer Permeability
2. Passive Transport Types
3. Simple Diffusion Mechanism
4. Facilitated Diffusion
5. Membrane Proteins in Diffusion
6. Water Movement Aquaporins
7. Active Transport Process
8. ATP-Driven Transport
9. Na⁺-K⁺ Pump Function
10. Secondary Active Transport
11. Endocytosis and Exocytosis
12. Cytotic Transport Characteristics

📖 1. Lipid Bilayer Permeability

🔑 Key Concepts & Definitions

• Hydrophobic nature of lipid bilayer limits permeability: The lipid bilayer's hydrophobic core creates a barrier that restricts the passage of polar molecules and ions, making the membrane selectively permeable (source content).
• Lipid bilayer as barrier to ions and polar molecules: Due to its hydrophobic interior, the lipid bilayer prevents ions and polar molecules from freely diffusing across, requiring specialized transport mechanisms (source content).
• Membrane permeability to small and hydrophobic molecules only: The membrane predominantly allows small, hydrophobic, lipid-soluble molecules such as O₂, CO₂, and steroids to pass via simple diffusion, without the involvement of membrane proteins (source content).
• Regulation of intracellular ionic concentrations through membrane permeability: Cells control internal ion levels by modulating membrane permeability, often through active transport or facilitated diffusion, to maintain homeostasis (source content).

📝 Essential Points