Transport Across Membranes

Flashcards on Transport Across Membranes

Selective Permeability

The ability to accumulate substances at different concentrations across a membrane.

Simple Diffusion

Movement across a membrane driven by concentration gradients.

Facilitated Diffusion

Movement across a membrane aided by transport proteins.

Active Transport

Movement across a membrane against a concentration gradient, requiring energy.

Membrane Potential

The difference in charge between the inside and outside of a cell membrane.

Osmosis

The movement of water across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.

Channel Proteins

Transport proteins that provide a path for specific molecules or ions to cross a membrane.

Ion Channels

Channel proteins that are highly selective for specific ions.

Gated Channels

Ion channels that open or close in response to a stimulus.

Porins

Transmembrane proteins that form pores on the membranes of mitochondria and are larger and less specific than ion channels.

Aquaporins

Proteins that facilitate the rapid passage of water across cell membranes.

Carrier Proteins

Transport proteins that undergo conformational changes to move molecules across a membrane.

Uniport

The transport of a single type of molecule across a membrane.

Coupled Transport

The transport of two or more different molecules across a membrane at the same time.

Symport

The transport of two different molecules in the same direction across a membrane.

Antiport

The transport of two different molecules in opposite directions across a membrane.

Direct Active Transport

Transport against a concentration gradient directly coupled to energy usage, such as ATP hydrolysis.

ATPases

Enzymes that hydrolyze ATP to transport solutes across membranes.

Indirect Active Transport

Active transport where the movement of one solute down its concentration gradient drives the movement of another solute up its concentration gradient.