Chapter 4

Front 1

passive transport

Back 1

The movement of substances acrosss a cell membrane without the use of energy by the cell.

Front 2

concentration gradient

Back 2

A difference in the concentration of a substance across a distance.

Front 3

equilibrum

Back 3

In chemistry, the state in which a chemical reaction and the reverse chemical reaction occur at the same rate such that the concentration of reactants and products do not change.

Front 4

diffusion

Back 4

The movement of particles from regionsof higher density to regions of lower density.

Front 5

osmosis

Back 5

The diffusion of water or another solvent from a more dilute solution to a more concentration solution through a membrane that is permeable to the solvent.

Front 6

hypertonic solution

Back 6

Describes a solution whose solute consentration is high than the solute concentration inside a cell.

Front 7

hypotonic solution

Back 7

Describes a solution whose solute concentration is lower than the solute concentration inside a cell.

Front 8

isotonic solution

Back 8

a solution whose solute concentration is equal to the solute concentration inside a cell.

Front 9

ion channel

Back 9

a pore in a cell membrane through which ions can pass.

Front 10

carrier proteins

Back 10

A protein that transports substances across a cell membrane.

Front 11

facilitated diffusion

Back 11

The transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins.

Front 12

active transport

Back 12

The movement of chemical substances, usually across the cell membrane, against a concentration gradient; requires cells to use energy.

Front 13

sodium-potassium pump

Back 13

A carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell.

Front 14

endocytosis

Back 14

The process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell.

Front 15

exocytosis

Back 15

The process by which aa substance is released from the cell through a vesicle that transports the substances to the cell surface and then fuses with the membrane to let the substance out.

Front 16

receptor protein

Back 16

A protein that binds specific signal molecules, which causes the cell to respond.

Front 17

second messenger

Back 17

A molecule that is generated when a specific substance attatches to a receptor on the outside of a cell membrane, which produces a change in cellular function.