Membrane Structure and Function

This set of flashcards covers essential vocabulary related to membrane structure and function, including transport mechanisms, membrane components, and biological processes.

Fluid Mosaic Model

A model describing the structure of cell membranes as a mosaic of various proteins floating in or on the fluid lipid bilayer.

Selective Permeability

The property of a membrane that allows certain substances to pass through while blocking others.

Passive Transport

The movement of molecules across a cell membrane without the use of energy, typically along a concentration gradient.

Facilitated Diffusion

The process of passive transport that uses transport proteins to help move molecules across the cellular membrane.

Active Transport

The process of moving molecules across a membrane against their concentration gradient, requiring energy.

Endocytosis

The process by which a cell takes in materials by engulfing them in a vesicle formed from the plasma membrane.

Exocytosis

The process of secretion of large molecules from a cell by the fusion of a vesicle with the plasma membrane.

Phagocytosis

A type of endocytosis known as 'cellular eating,' where a cell engulfs large particles or organisms.

Pinocytosis

A type of endocytosis known as 'cellular drinking,' where a cell engulfs small particles and liquids.

Receptor-Mediated Endocytosis

A specialized form of endocytosis that uses receptor proteins to selectively bind and uptake specific molecules.

Cholesterol Function

Cholesterol stabilizes cell membranes and affects fluidity, acting as a temperature buffer.

Sodium-Potassium Pump

An active transport mechanism that moves sodium out of and potassium into cells against their concentration gradients.

Ion Channels

Proteins that allow ions to pass through the membrane; can be gated to open or close in response to signals.

Aquaporins

Channel proteins that facilitate water transport across the cell membrane.

Concentration Gradient

A difference in the concentration of a substance across a space, which drives passive transport.

Hydrophobic Interaction

Interactions that occur between nonpolar molecules in an aqueous environment, playing a key role in membrane structure.

Membrane Proteins

Proteins associated with the lipid bilayer that perform various functions, including transport and signaling.

Transmembrane Proteins

Proteins that span the entire lipid bilayer and can facilitate transport across the membrane.

Peripheral Proteins

Proteins that are loosely bound to the surface of the membrane or to integral proteins.

Cotransport

A form of active transport in which the movement of one molecule down its gradient drives the movement of another molecule against its gradient.

Hydrophobic Tails

The nonpolar (fatty acid) part of phospholipids that faces inward, away from water in the lipid bilayer.

Hydrophilic Heads

The polar (water-attracting) part of phospholipids that faces outward, towards the water.

Membrane Fluidity

The viscosity of the lipid bilayer, which affects the movement of proteins and lipids within the membrane.

Hypertonic Solution

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

Hypotonic Solution

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

Isotonic Solution

A solution where the concentration of solutes is equal in and out of a cell, resulting in no net movement of water.