Transport Across Membranes: Overcoming the Permeability Barrier

These flashcards cover key concepts related to transport across membranes, including different types of transport mechanisms and their definitions.

Simple Diffusion

The unaided movement of molecules across a membrane from an area of higher concentration to an area of lower concentration.

Facilitated Diffusion

The process of transporting substances across a membrane from high to low concentration with the help of transport proteins, without energy expenditure.

Active Transport

The movement of substances across a cell membrane against their concentration gradient, requiring energy, often derived from ATP.

Osmosis

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

Uniport

Transport of a single solute across a membrane by a carrier protein.

Symport

Coupled transport of two solutes in the same direction across a membrane.

Antiport

Coupled transport of two solutes in opposite directions across a membrane.

Direct Active Transport

Transport of a solute against its gradient directly coupled to an exergonic chemical reaction, such as ATP hydrolysis.

Indirect Active Transport

Transport of a solute against its gradient driven by the favorable movement of another solute down its gradient.

Hypertonic Solution

A solution that has a higher solute concentration compared to another solution, leading to water moving out of cells.

Hypotonic Solution

A solution that has a lower solute concentration compared to another solution, leading to water moving into cells.