Transport Across Cell Membranes

rapid change in membrane potential because of changes in the flux of potassium and sodium ions inside and outside the cell

cotransport of two substrates by a membrane transport protein in which the substrates cross the membrane in opposite directions

transmembrane ATPase that pumps Ca²⁺ ions out of the cytosol and into either the extracellular space or a calcium-sequestering organelle

protein that physically binds to a molecule and facilitates its transport across the cell membrane's lipid bilayer

protein that creates a pathway with a hydrophilic (having a strong affinity to water) interior for ions or polar molecules to pass through

transmembrane protein that transports one substrate against its gradient by coupling it to a transport of a second substrate down its gradient

change of the voltage across the membrane above resting membrane potential. It is the opposite of hyperpolarization.

membrane-bound ATPase that generates a proton gradient. Some may be run in reverse to synthesize ATP.

change in the voltage across the membrane below resting membrane potential. It is the opposite of depolarization.

transmembrane protein that creates a hydrophilic (having a strong affinity to water) channel with a specificity filter that allows a single type of ion to pass through

molecule that binds to a specific receptor protein

double layer of lipids that separates the cell interior from the external environment and regulates the passage of substances into and out of the cell

membrane that encloses a cell and is made of layers of lipids, organic molecules made of carbon and hydrogen

ungated channel specific for K⁺ ions that aids in maintaining resting membrane potential

transmembrane ATPase that pumps sodium ions out of the cell and potassium ions into the cell

cotransport of two substrates by a membrane transport protein in which the substrates cross the membrane in the same direction

protein that spans a lipid membrane and uses ATP hydrolysis to transport a substrate across the membrane against its concentration gradient

transmembrane protein that transports a substrate across the membrane, either by facilitated diffusion down the gradient or by cotransport against the gradient of one substrate and down the gradient of the other

receptor that acts as a gate allowing ions into or out of the cell in response to a change in electrical charge across the membrane