Primary active transport
Transport of substance against a concentration (or electrochemical) gradient; across the plasma membrane by a solute pump; directly uses energy of ATP hydrolysis
Second active transport
cotransport (coupled transport) of two solutes across the membrane; energy is supplied by the ion gradient created by a primary active solute pump (indirectly); symporters move the transported substances in the same direction; antiporters move transported substances in opposite directions across the membrance.
exocytosis vesicular transport
moving substance out of the cell; Secretion or ejection of sustances from a cell; the substance is enclosed in a membranous vesicle; which fuses with the plasma membrane and reptures; releasing the substance to the exterior
Cell eating: A large external particle (protein, bacteria, dead cell debris) is surrounded by a "seizing foot" and becomes enclosed in a vesicle (phagosome)
fluid-phase endocytosis, Plasma membrane sinks beneath an external fluid droplet containing small solutes; membrane edges fuse, forming a fluid-filled vesicle; clathrin-coated vesicles formed.
Selective endocytosis and transcytosis; external substance binds to membrane receptors, and clathrin-coated pits are formed
Via caveolin-coated vesicles
Selective endocytosis (and trascytosis); external substance binds to membrane receptors (often associated with lipid rafts); caveolin-coated vesicles formed
Via coatomer-coated vesicles
vesicles coated with coatomer proteins pinch off from organelles and travel to other organelles to deliver their cargo
Secondary active transport examples
Movement of polar or charged sulutes, e.g., amino acids (into cell by symporters); Ca2+, H+ (out of cells via antiporters)
Exocytosis vesicular transport examples
Secrection of neurotransmitters, hormones, mucus, etc.; ejection of cell wastes
In the human body, occurs primarily in protective phagocytes (some white blood cells and macrophages)
Occurs in most cells; important for taking in dissolved soultes by absorptive cells of the kidney and intestine.
Receptor-mediated endocytosis examples
Means of intake of some hormones, cholesterol, iron, and most macromolecules.
Via caveolin-coated vesicles examples
Roles not fully know; proposed roles include choldsterol regulation and trafficking; platforms for signal transduction