Transport Across the Plasma Membrane Flashcards

Vocabulary flashcards based on lecture notes about transport mechanisms across the plasma membrane.

Primary Active Transport

Energy is directly derived from the hydrolysis of ATP.

Na+/K+ ATPase Pump

An example of primary active transport; generates a net current and is electrogenic.

Non-Mediated Transport

Transport that does not directly use a transport protein

Diffusion

Diffusion directly through the lipid bilayer.

Nonpolar hydrophobic molecules

Molecules that can traverse/cross the hydrophobic core.

Mediated Transport

Moves materials with the help of a transport protein.

Diffusion Through Ion Channels

Diffusion through channels that form a water-filled pore.

Ionic Selectivity

Property of channels; specific amino acids lining the pore determine the selectivity of the channel to ions.

Gating

Property of channels; contain gates that control opening and closing of the pore.

Electrical Current

Property of channels; diffusion of ions generating a measurable current.

Carrier Mediated Transport

Substrate directly interacts with the transporter protein; slower transport rates.

Properties of Carrier Mediated Transport

Exhibiting specificity, inhibition, competition, saturation.

Mediated Transport

Transport proteins mediate transport across the cell membrane at a faster than normal rate.

Passive Transport

Moves substances down their concentration or electrochemical gradient using only their kinetic energy.

Facilitated Diffusion of Glucose

Glucose binds to transport protein (GLUT), transporter protein changes shape.

Active Transport

Uses energy to drive substances against their concentration or electrochemical gradients.

Na+ Pump

Maintains a low concentration of Na+/high concentration of K+ in the cytosol.

Secondary Active Transport

Energy stored in an ionic concentration gradient is used to drive the active transport of a molecule against its gradient.

Na+ Antiporter/Exchanger

Na+ ions rush inward, Ca2+ or H+ pushed out.

Na+ Symporters/Cotransporters

Glucose or amino acids rush inwards together with Na+ ions.

Harnessing Energy in Ion Gradients

Where Na+ pumps use energy from the hydrolysis of ATP directly to make a higher concentration of Na+ outside the cell.

Facilitated Diffusion

Passive transport that needs a transport protein.

Ion Selectivity Filter

The filter on a channel that only allows certain ions to pass.

Low Na+/High K+ Concentrations

This maintains resting membrane potential, electrical excitability, and contraction of muscle.

Pump-Leak Hypothesis

The hypothesis maintaining that the Na+/K+ pump works continuously to counter the constant leaking of those ions.