Structure & Function of Plasma Membranes

These flashcards cover key concepts regarding the structure and function of plasma membranes, including components, transport mechanisms, and membrane properties.

Fluid Mosaic Model

A model that describes the plasma membrane as a fluid structure with a 'mosaic' of various proteins embedded in it.

Asymmetrical Membrane

A characteristic of plasma membranes where the inner and outer surfaces differ in composition and protein arrangement.

Selective Permeability

The property of a cellular membrane that allows certain molecules to pass through more easily than others.

Integral Proteins

Membrane proteins that are embedded completely within the membrane and possess both hydrophobic and hydrophilic regions.

Peripheral Proteins

Proteins that are not embedded in the lipid bilayer and are usually found on the surface of the membrane.

Phospholipids

Amphipathic molecules that form the basic structure of the plasma membrane, consisting of hydrophilic heads and hydrophobic tails.

Cholesterol

A type of sterol that helps to regulate the fluidity of the plasma membrane.

Facilitated Diffusion

A type of passive transport that uses transmembrane proteins to move substances down their concentration gradient.

Osmosis

The movement of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.

Active Transport

The movement of molecules across a membrane against their concentration gradient, requiring energy in the form of ATP.

Endocytosis

The process by which cells take in substances by vesicle formation from the plasma membrane.

Exocytosis

The process by which cells export substances out of the cell via vesicles fusing with the plasma membrane.

Hydrophilic

Substances that are attracted to water and can interact with the aqueous environment.

Hydrophobic

Substances that repel water and do not interact well with aqueous environments.

Aquaporins

Channel proteins specifically designed for the transport of water across the plasma membrane.

Glycoproteins

Proteins with carbohydrate groups attached that play a key role in cell-cell recognition and communication.

Tonicity

The ability of a solution to cause a cell to gain or lose water, categorized as isotonic, hypotonic, or hypertonic.

Electrochemical Gradient

The combined effect of concentration gradient and electrical gradient that affects the movement of ions across membranes.

Cotransport

A method of active transport where two substances are transported simultaneously across a membrane.

Sodium-Potassium Pump

A primary active transport mechanism that moves sodium ions out of and potassium ions into the cell against their concentration gradients.

Bulk Transport

Transport mechanisms that move large molecules or particles into or out of the cell, either through endocytosis or exocytosis.