Cell Membrane Structure and Protein Functions Quiz

Cell Membranes

• The fluid-mosaic model describes the structure of cell membranes, which consist of a phospholipid bilayer with embedded proteins, allowing for selective permeability.

Protein Functions in Cell Membranes

• Proteins in cell membranes perform six main functions:
  • Receptors for signal transduction
  • Enzymes for catalyzing chemical reactions
  • Transporters for moving molecules across the membrane
  • Cell-cell recognition and adhesion
  • Anchoring the cytoskeleton
  • Cell signaling and communication

Selective Permeability

• Selectively permeable cell membranes allow certain molecules to pass through while restricting others, maintaining internal cellular conditions.

Diffusion and Active Transport

• Diffusion is the passive movement of molecules from an area of high concentration to an area of low concentration, resulting in uniform distribution.
• Active transport, in contrast, is the energy-dependent movement of molecules against their concentration gradient, often requiring ATP.

Facilitated Diffusion

• Facilitated diffusion is a type of passive transport in which molecules move down their concentration gradient with the assistance of transport proteins, but does not require energy input.