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Study Guide for the Cell Processes Assessment
Cell membrane- made of phospholipid molecules, has protein channels in it and is
selectively permeable (allows certain molecules in or out by diffusion)
diffusion - The movement of molecules from a region of higher concentration to a
region of lower concentration. (An example of diffusion is when a drop of blue
dye is put in water and it spreads out turning all of the water blue.)
osmosis –The diffusion of water through a membrane. Water moves through a plant or
vegetable by osmosis.
equilibrium- occurs when all the particles are equally spread out on both sides of the
membrane
Cellular Transport:
There are several ways materials move into and out of cells. The cell membrane
is selectively permeable which allows the movement of some substances, into or out of
the cell. Many particles, such as water and oxygen, are tiny enough that they can
diffuse directly through the cell’s membrane, which is made of phospholipid molecules.
Particles that are too big to squeeze through the cell’s membrane must enter through
protein doorways.
passive transport - The movement of particles, through a protein doorway, from a
more crowded to a less crowded area WITHOUT the use of energy.
active transport – The movement of particles, through a protein doorway, from an area
of low concentration to an area of high concentration WITH the use of ATP
(energy).
endocytosis – “within the cell” -the process in which a cell membrane surrounds a
larger particle and encloses it in a vesicle to bring it into the cell.
exocytosis – “outside the cell” -the process in which vesicles are formed at the Golgi
complex and carry the particle to the cell’s membrane for release out of the cell.