Transport mediated by a membrane transport protein; three types: uniport, symport, antiport. Used to transport molecules that cannot pass through membrane by simple diffusion (too large, lipophobic or electrically charged)
Passive and moves molecules down their concentration gradient and the net transport stops when concentrations are equal on both sides of the membrane; requires no input or energy from outside source.
Moves molecules across membranes; two types: channel proteins and carrier proteins.
Create water-filled passageways that link intracellular and extracellular compartments.
Carriers that bind to a substrate that they carry.
Channels that are made from a protein called aquaporin.
Channels that may be specific for one ion or may allow ions of similar size and charge to pass.
Channels that allow ions to move back and forth across the membrane without regulation; also called leak channels.
Channels that spend most of their time closed which allows the channels to regulate the movement of ions through them.
Channels that use intracellular messenger molecules or extracellular ligands to control the gating.
Chemically Gated Channels
Gating that is controlled by the electrical state of the cell.
Voltage Gated Channels
Gating that can be controlled by any physical change.
Mechanically Gated Channels
Carrier proteins that move only one kind of molecule.
Carrier that moves more than one kind of molecule.
Molecules being transported that are moving in the same direction whether into or out of the cell.
Molecules that are being transported in the opposite direction of each other.
The energy used to push molecules against their concentration gradient that comes directly from the high energy phosphate bond of ATP.
Primary Active Transport
Potential energy stored in the concentration gradient of one molecule is used to push other molecules against their concentration gradients.
Secondary Active Transport
The point at which increases in concentration do NOT result in an increase of movement of a substance across the membrane.
The ability of a carrier to move one molecule or only a group of closely related molecules.
A transporter may move several members of a related group of substances but those substrates will compete with one another for the binding sites on the transporter.
Rate that depends on both the substrate concentration and the number of carrier molecules.
Regions of protein molecule that open and shut controlling flow.
Diffusion that happens directly across the phospholipid bilayer.
Ingestion of bacteria or other material of phagocytes.
Vacuole in cytoplasm of cell containing a phagocytosed particle enclosed within a part of the cell membrane.
Ingestion of a liquid into a cell by the budding of small vesicles from the cell membrane.
Process by which cells internalize molecules by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecule being internalized.
Receptor Mediated Endocytosis
Reuse of the ligands receptors.
Intracellular vesicles move to cell membrane and fuse with it; then their contents are released to extracellular fluid.
Combination of endocytosis, vesicular transport across the cell, and exocytosis; macromolecules that are transported across interior of cell.
Taking in of matter by a living cell by invagination of its membranes to form a vacuole.