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Does exocytosis require ATP?

Bernoull

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    Exocytosis involves the fusing of the vesicle membrane with the plasma membrane and the emptying of the vesicle's contents to the cell's exterior. I don't see where energy is required here.

    However, I won't be surprised if earlier steps require energy, for instance concentrating chemical/protein X within the vesicle or how is the vesicle directed to the cell membrane as opposed to the nuclear membrane. I know the vesicles are chemically tagged which I'm sure uses energy..

    my $0.02...
     
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      Exocytosis DOES require energy. Think about it, you're breaking and forming chemical bonds. Not to mention getting the vesicle to the membrane, binding it, incorporating it, etc. etc. It's not actually just some fatty vesicle that floats through the cytosol and binds willy nilly to the membrane then it's out. If you are interested in it though, it's a fascinating process and a good cell book would have it in there.

      It's a lot more complicated than that, but if it is on the MCAT it will be in a passage.
       

      AliDeLaLouisa

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      Jun 10, 2009
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        :)
        Bulk transport
        Exocytosis

        Energy Source:
        ATP


        Secretion or ejection of sub- stances from a cell: the sub- stance is enclosed in a membranous vesicle. which fuses with the plasma membrane and ruptures. Releasing the substance to the exterior

        Example:
        Secretion of neurotransmitters, hormones, mucus, etc; ejection of cell wastes
        Phagocytosis (endocytosis) ATP'Cell eating" A large external particle (proteins. bacteria. dead cell debris) is surrounded by a "seizing foot" and becomes enclosed in a plasma membrane sacIn the human body, occurs primarily in protective phagocytes (some white blood cells, macrophages)Pinocytosis (endocytosis) ATP'Cell drinking" Plasma membrane sinks beneath an external fluid droplet containing small solutes: membrane edges fuse. forming a fluid- filled vesicleOccurs in most cells; important for taking in solutes by absorptive cells of the kidney and
        intestineReceptor-mediated
        endocytosisATPSelective endocytosis process. external substance binds to membrane receptors. and coated pits are formedMeans of intake
        of some hormones, cholesterol, iron, and other molecules

        [SIZE=+1]Bulk Transport: Large particles and macromolecules are transported through plasma membranes by bulk transport. Like solute pumping. bulk transport is energized by ATP. The two kinds of bulk transport are[/SIZE]
        [SIZE=+1]oxocytosis and endocytosis.[/SIZE] [SIZE=+1]Exocytosis: (ek"-so-si-to'-sis) is the mechanism by which substances are moved from the cell interior into the extracellular space. It accounts for hormone secretion, Neurotransmitter release, mucus secretion, and, in some cases, the ejection of wastes. In exocytosis, the substance or cell product to be released is first enclosed within a membranous sac.:)[/SIZE]
         
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