Transport Across Membranes: Overcoming the Permeability Barrier

Flashcards covering key concepts related to membrane transport mechanisms, including definitions and types of transport.

Selective Permeability

The property of biological membranes that allows certain substances to pass through while others cannot.

Simple Diffusion

The passive movement of solute molecules from an area of higher concentration to an area of lower concentration without the need for energy.

Facilitated Diffusion

The process of transporting molecules across a membrane via proteins, without energy expenditure, moving from higher to lower concentration.

Active Transport

The process of moving solutes against their concentration gradient, requiring energy, often from ATP hydrolysis.

Osmosis

The diffusion of water across a selectively permeable membrane, moving towards the area of higher solute concentration.

Uniport

A transport mechanism in which a carrier protein transports a single solute across a membrane.

Symport

A type of coupled transport where two solutes are transported in the same direction across a membrane.

Antiport

A type of coupled transport where two solutes are transported in opposite directions across a membrane.

Direct Active Transport

Active transport that is directly coupled to an energy source, typically the hydrolysis of ATP.

Indirect Active Transport

Active transport that relies on the movement of one solute down its gradient to drive the movement of another solute against its gradient.

Hypertonic Solution

A solution with a higher concentration of solutes compared to another solution, leading to water moving out of the cell.

Hypotonic Solution

A solution with a lower concentration of solutes compared to another solution, causing water to enter the cell.

Carrier Proteins

Integral membrane proteins that facilitate the transport of substances across a membrane by undergoing conformational changes.

Channel Proteins

Integral membrane proteins that provide passageways for solutes to move across membranes through hydrophilic channels.

Energy Source in Active Transport

Usually ATP is the primary energy source for active transport mechanisms.

Isotonic Environment

A condition in which the solute concentration outside the cell is equal to that inside the cell, preventing net movement of water.