Bio Ch. 5 (From textbook)

Solute

A substance that is dissolved in a solution. Salt, sugar...

Solvent

A liquid substance capable of dissolving other substances. ("universal solvent\=water")

passive transport

movement of substances across a cell membrane without the use of energy.

diffusion

movement of particles from regions of higher density to lower density; a type of passive transport

concentration gradient

difference in the concentration of a substance across a distance.

equilibrium

state that exists when the concentration of a substance is the same throughout a space.

osmosis

Diffusion of water through a selectively permeable membrane. From high concentration to low concentration of water. A form of passive transport.

hypotonic

solution whose solute concentration is lower than the solute concentration inside a cell (e.g. an over-watered plant). Water moves into cell more causing a swelling.

hypertonic

solution whose solute concentration is higher than the solute concentration inside a cell (e.g. an under-watered plant). Water leaves cell causing shrinkage of cell.

isotonic

solution whose concentration is equal to the solute concentration inside a cell (a healthy plant). Water inside and outside cell are in equilibrium. Same amount leaving and entering the cell.

contractile vacuole

in protists, an organelle that accumulates water and then releases it periodically to maintain osmotic pressure.

turgor pressure

pressure that is exerted on the inside of cell walls and that is caused by the movement of water into the cell.

plasmolysis

the contraction or shrinking of the cell membrane of a plant cell in a hypertonic solution in response to the loss of water by osmosis. Plant will wilt.

cytolysis

the bursting of a cell.

facilitated diffusion

the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins; a type of passive transport

carrier protein

a protein that transports substances across a cell membrane.

ion channel

a complex of protein molecules in a cell membrane that form a pore through which ions can pass.

active transport

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

sodium-potassium pump

a carrier protein that uses ATP to actively transport 3 sodium ions out of a cell and 2 potassium ions into the cell at a time.

endocytosis

cell membranes surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell; a type of active transport

pinocytosis

a method of active transport across the cell membrane in which the cell takes in extracellular fluids.

phagocytosis

the process by which a cell engulfs large particles or whole cells, either as a defense mechanism or as a means to obtain food.

phagocyte

a cell that ingests and destroys (digests) foreign matter or microorganisms.

exocytosis

when a vesicle transports substances to the cell surface to let the substance out of the cell; a type of active transport

selectively permeable

allowing certain substances to pass through it but not others

receptor-mediated endocytosis

The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.

Aquaporins

water channel proteins

Gated Channel Protein

A transport protein that opens a "gate," allowing a molecule to flow through the membrane.