Membrane Structure & Function

These flashcards cover key vocabulary and concepts related to membrane structure and function, including types of transport and cellular mechanisms.

Phospholipids

Most abundant lipid in the plasma membrane, amphipathic molecules containing hydrophobic and hydrophilic regions.

Fluid Mosaic Model

Describes the plasma membrane as a mosaic of protein molecules in a fluid bilayer of phospholipids.

Membrane Fluidity

Determined mainly by weak hydrophobic interactions; cholesterol can reduce fluidity at moderate temperatures.

Peripheral Proteins

Proteins bound to the surface of the membrane.

Integral Proteins

Proteins that penetrate the hydrophobic core of the membrane.

Diffusion

The tendency for molecules to spread out evenly into the available space, moving from high to low concentration.

Brownian Movement

The random movement of particles suspended in a fluid or gas, driving diffusion.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Facilitated Diffusion

The process where transport proteins speed up the passive movement of molecules across the plasma membrane.

Active Transport

The movement of substances against their concentration gradient, requiring energy.

Sodium-Potassium Pump

A specific type of active transport system used by animal cells to maintain concentration gradients of sodium and potassium ions.

Membrane Potential

The voltage across a membrane created by differences in the distribution of ions.

Exocytosis

The process where transport vesicles fuse with the membrane to release contents outside the cell.

Endocytosis

The process by which cells take in macromolecules by forming vesicles from the plasma membrane.

Phagocytosis

Cellular eating, the engulfing of a particle in a vacuole of a cell.

Pinocytosis

Cellular drinking, uptake of molecules dissolved in small droplets.

Receptor-Mediated Endocytosis

Vesicle formation triggered by the binding of specific solutes to receptors.