Vocabulary Vocabulary ReviewReview

Homeostasis andHomeostasis and

Cell TransportCell 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 energyActive

Transport

A carrier protein that uses ATP to

actively transport sodium ions out of

a cell and potassium ions

into the cellSodium-

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 cellEndocytosis

Small cavity or sac that contains

materials; forms when part of the

membrane surrounds the materials to be

taken into or out of the cellVesicle

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

foodPhagocytosis

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