Cell Membrane Structure and Functions

Cell Membrane Structure

• Phospholipid bilayer: composed of two layers of phospholipid molecules with their hydrophobic (non-polar) tails facing inward and hydrophilic (polar) heads facing outward
• Thickness: approximately 7-10 nanometers (nm)
• Semipermeable: allows certain molecules to pass through while keeping others out

Cell Membrane Functions

• Regulates what enters and leaves the cell
• Maintains cell shape and provides mechanical support
• Acts as a barrier against external substances
• Plays a role in cell signaling and communication

Cell Membrane Components

• Phospholipids: amphipathic molecules that make up the majority of the bilayer
• Proteins: embedded in the bilayer, facilitate transport, signaling, and cell-cell interactions
• Cholesterol: helps maintain membrane fluidity and structure
• Carbohydrates: attached to proteins and lipids, involved in cell-cell recognition and signaling

Cell Membrane Transport

• Passive transport: movement of molecules from high to low concentration without energy input
  • Diffusion: movement of molecules from high to low concentration
  • Osmosis: movement of water molecules through the membrane
• Active transport: movement of molecules from low to high concentration using energy input
  • Carrier proteins: transport molecules across the membrane
  • Pumping mechanisms: use energy to move molecules against their concentration gradient

Fluid Mosaic Model

• Describes the cell membrane as a dynamic, fluid structure with proteins and lipids able to move laterally
• Supports the idea of a semi-fluid membrane that allows for membrane transport and cellular processes

Test your knowledge of cell membrane structure, functions, and transport mechanisms. Learn about phospholipid bilayer, protein, and cholesterol composition, as well as passive and active transport processes. Understand the fluid mosaic model and its significance in cellular biology.