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Explore the processes of endocytosis and exocytosis in cellular transport. Endocytosis involves engulfing extracellular fluid and materials, while exocytosis restores the balance of the plasma membrane. Discover more with helpful resources.
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Cellular Transport EndocytosisExocytosis LS.3
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endocytosis.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endocytosis.html • Endocytosis • In endocytosis, the cell engulfs some of its extracellular fluid (ECF) including material dissolved or suspended in it. A portion of the plasma membrane is invaginated and pinched off forming a membrane-bounded vesicle called an endosome.
Endocytosis removes portions of the plasma membrane and takes them inside the cell. To keep in balance, membrane must be returned to the plasma membrane. This occurs by exocytosis.
Exocytosis Exocytosis is the reverse of endocytosis. • And that is just as well. In 30 minutes an active cell like a macrophage (right) can endocytose an amount of plasma membrane equal to its complete plasma membrane. • This electron micrograph (courtesy of Dr. Robert J. North) shows a guinea phagocyte ingesting polystyrene beads. Several beads are already enclosed in vacuoles while the others are in the process of being engulfed. • So the cell must have a mechanism to restore the normal amount of plasma membrane. Exocytosis is that mechanism.
More Resources • http://academic.brooklyn.cuny.edu/biology/bio4fv/page/endocyta.htm (endocytosis and exocytosis) • http://personal.tmlp.com/Jimr57/textbook/chapter3/cmf4a.htm The Virtual Cell Web Page (endocytosis and exocytosis) • http://www.bbc.co.uk/education/asguru/biology/01cellbiology/05pathways/09endoexo/index.shtml (endocytosis and exocytosis) • http://www.wisc-online.com/objects/index_tj.asp?objID=AP11403 • Typical Animal Cell---Interactive • http://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/cell_structure.htm • Cell Structure—Interactive