Vocabulary Review
Homeostasis and
Cell Transport
The movement of
substances across a
cell membrane without
any input of energy
Passive Transport
The movement of
molecules from an
area of higher
concentration to an
area of lower
concentration
Diffusion
The difference in the
concentration of
molecules across a
distance
Concentration
gradient
Concentration of
molecules is the same
throughout the space
the molecules occupy
Equilibrium
Movement of water
molecules from high
concentration to low
concentration
Osmosis
Concentration of solute
molecules outside the
cell is LOWER than in
the cytosol; water
diffuses into the cell
Hypotonic
Concentration of solute
molecules outside the
cell is HIGHER than in
the cytosol; water
diffuses out of the cell
Hypertonic
Concentrations of
solutes outside and
inside the cell are
equal
Isotonic
Organelles that
remove water through
contraction
Contractile
Vacuoles
The pressure that
water molecules exert
against the cell wall
Turgor pressure
The shrinking of a cell
due to water’s moving
out the cell when placed
in a hypertonic
environment
Plasmolysis
The swelling and
eventual bursting of a
cell as water moves into
it when placed in a
hypotonic environment
Cytolysis
The movement of
substances across a
cell membrane with
the assistance of
protein carriers
Facilitated
Diffusion
The proteins that
move certain
molecules into the cell
that cannot readily
diffuse through the
cell membrane
Carrier Proteins
A complex of protein
molecules in a cell
membrane that form
a pore through which
ions can pass
Ion Channels
The movement of
chemical substances,
usually across the cell
membrane, against a
concentration gradient;
requires energy
Active Transport
A carrier protein that
uses ATP to actively
transport sodium ions
out of a cell and
potassium ions into
the cell
Sodium-Potassium
Pump
The process by which a
cell membrane surrounds
a particle and encloses
the particle in a vesicle
to bring the particle
into the cell
Endocytosis
Small cavity or sac that
contains materials;
forms when part of the
membrane surrounds the
materials to be taken
into or out of the cell
Vesicle
A method of active
transport across the
cell membrane in
which the cell takes
in extracellular fluids
Pinocytosis
The process by which a
cell engulfs large
particles or whole cells,
either as a defense
mechanism or as a
means to obtain food
Phagocytosis
A cell that ingests
and destroys (digests)
foreign matter or
microorganisms
Phagocyte
The process by which a
substance is released from
the cell through a vesicle
that transports the
substance to the cell
surface and then fuses
with the membrane to let
the substance out
Exocytosis