Biological Membranes

Biological Membranes

Composed of lipid, protein, and carbohydrate; serve as boundaries between internal and external environments of cells.

Lipid Bilayer

Double layer of phospholipids that forms the main structural component of biological membranes.

Fluid Mosaic Model

Dynamic structure of the membrane where proteins and lipids move freely within the lipid bilayer.

Passive Transport

Movement of molecules across the membrane without the use of energy, including osmosis, simple diffusion, and facilitated diffusion.

Primary Active Transport

Energy-dependent movement of molecules across the membrane using ATP and carrier proteins.

Bulk Transport

Large-scale movement of molecules across the membrane through endocytosis and exocytosis.

Secondary Active Transport

Energy-dependent movement of molecules across the membrane using the energy generated by the simultaneous transport of other molecules.

Donnan Membrane Equilibrium

Unequal distribution of ions across a semipermeable membrane due to the presence of non-diffusible anions.

Na+/K+ Pump

Counterbalances the effect of Donnan equilibrium by actively transporting sodium ions out of the cell and potassium ions into the cell.

Ionic Movement

Occurs across capillary walls, allowing for the exchange of ions between the blood and surrounding tissues.