Membrane Transport Mechanisms

Vocabulary flashcards covering key terms and concepts related to membrane transport mechanisms.

Fluid Mosaic Model

A model that describes the structure of biological membranes as a mosaic of diverse protein molecules embedded in a fluid phospholipid bilayer.

Passive Transport

The movement of substances across a cell membrane without the use of energy. Includes diffusion and facilitated diffusion.

Diffusion

The movement of atoms, molecules, and ions from regions of high concentration to regions of low concentration.

Facilitated Diffusion

A process by which substances move across membranes with the help of transport proteins, bypassing the lipid bilayer.

Osmosis

The diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Active Transport

The process of moving substances across a cell membrane against their concentration gradient, requiring energy (ATP).

Carrier Proteins

Proteins that transport specific substances across a cell membrane by changing shape and never providing a continuous passage.

Channels

Proteins that form passageways in the membrane allowing ions to move through; these can be passive and often selective.

Uniporter

A type of carrier that transports a single type of molecule down its electrochemical gradient.

Symporter

A carrier that transports one type of molecule downhill while using its energy to move another type of molecule uphill, both in the same direction.

Antiporter

A carrier that transports two types of molecules in opposite directions, one typically moving into and the other out of the cell.

Gated Channels

Channels that open or close in response to stimuli, allowing selective passage of ions or molecules.

Pores

Always open channels that allow continuous passage for certain molecules across the membrane.

Primary Active Transport

Transport that moves substances against their electrochemical gradient using energy directly from ATP.

Secondary Active Transport

Transport that moves substances across plasma membrane with the energy from an existing concentration gradient, usually established by primary active transport.

Concentration Gradient

The difference in concentration of a substance across a space; the greater the difference, the faster the rate of diffusion.