Transcript Cellular Transport

Cellular Transport
Endocytosis
Exocytosis
LS.3
http://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
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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