Secretory vesicles are transported -
Ans. is 'd' i.e., Have no relation with concentration gradientExoevtosiso Exoevtosis is a reverse of endocytosis. This process is involved when secretory granules are extruded from the cell. When secretory vesicle comes in contact with inside of cell membrane, the membrane of the vesicle fuses with cell membrane and then there is extrusion of the contents of vesicle from the cells as secretory granules. Similar to endocytosis exoevtosis requires Ca++ and energy. Exoevtosis is also called emiocytosis or reverse pinoevtosis.o Exoevtosis (secretion from the cell) occurs via two pathways : -Non-constitutivepathway:- Proteins from the Golgi apparatus initially enter secretory' granules, where processing of prohormones to mature hormones occurs before exocytosis. This pathway is sometimes called "regulated pathway".Constitutive pathway :- Involves the prompt transport of proteins to the cell membrane in vesicles, with little or no processing or storage.Types of transport across cell membrane Carrier protein involvedEnergy requiredConcentration gradientSimple diffusionNoNoAlong (Down hill)Osmosis (Diffusion of H.O)NoNoAlong (Down hill)Facilitated diffusionYesNoAlong (Down hill)Active transportYesYesAgainst (Uphill)ExocytosisNoYesN/A (not applicable)Endocytosisy Pinocytosis & Phagocytosisy Receptor mediated endocytosisNoYesYesYesN/AN/A
Along concentration gradient
Against concentration gradient
May be along or against concentration gradient
Have no relation with concentration gradient
Pituitary