Chapter 7 p2: Membrane structure and function – Transport across membranes

Vocabulary flashcards covering key membrane transport concepts from the notes.

Plasma membrane

The phospholipid bilayer that encloses the cell and regulates traffic into and out of the cell.

Passive transport

Movement of substances across the membrane that does not require energy, often along a concentration gradient and sometimes aided by transport proteins.

Vesicle exocytosis

Process by which secretory vesicles fuse with the plasma membrane to release contents outside the cell.

Endocytosis

Process by which the plasma membrane engulfs material to form vesicles that bring material into the cell.

Active transport

Movement of substances across a membrane against their concentration gradient, requiring energy (typically ATP) and transport proteins.

Facilitated diffusion

Passive transport that requires a transport protein to move substances down their concentration gradient.

Carrier protein

Transport protein that binds a solute and changes shape to shuttle it across the membrane.

Conformational change

Shape change of a transport protein triggered by binding and release of the transported molecule.

Gated channels

Ion channels that open or close in response to a signal, such as a ligand, enabling ion flow.

Acetylcholine

A neurotransmitter that binds to receptors to trigger channel opening in some neurons.

Sodium-potassium pump (Na+/K+ ATPase)

An ATP-driven pump that exports 3 Na+ for every 2 K+ imported, generating a membrane potential.

Proton pumps

Electrogenic pumps that move protons across membranes (in plants, bacteria, and fungi) to create electrochemical gradients.

Electrochemical gradient

The combined chemical (concentration) and electrical (voltage) forces that drive ion diffusion across membranes.

Membrane potential

Voltage difference across the membrane caused by ion distribution, typically negative inside.

Uniport

Transport of a single substance in one direction across a membrane.

Symport

Co-transport where two different substances are moved in the same direction, often driven by a gradient.

Antiport

Co-transport where two substances move in opposite directions across the membrane.

Sodium-Glucose symporter

A symporter that uses the Na+ gradient to drive glucose uptake into the cell.

Receptor-mediated endocytosis

Endocytosis triggered when ligands bind to specific receptors, clustering in coated pits.

Endosome

A vesicle formed during endocytosis that carries ingested material inside the cell.