Cell Membrane & Transport - Biol 120

These flashcards cover key concepts related to cell membranes and transport mechanisms, including definitions and important processes.

Cell Membrane

The boundary that separates the living cell from its non-living surroundings.

Selective Permeability

The ability of the plasma membrane to allow certain substances to cross it more easily than others.

Phospholipid Bilayer

A double layer of phospholipids that forms the core of the plasma membrane.

Amphipathic Molecules

Molecules with both hydrophobic and hydrophilic regions, such as phospholipids.

Fluid Mosaic Model

The model that describes membranes as a fluid structure with a mosaic of various proteins embedded within.

Flippase

An enzyme that moves phospholipids from the outer leaflet to the inner leaflet of the membrane.

Floppase

An enzyme that moves phospholipids from the inner leaflet to the outer leaflet of the membrane.

Membrane Proteins

Proteins that determine the specific functions of the membrane, including integral and peripheral proteins.

Facilitated Diffusion

Transport proteins aid the movement of molecules across the plasma membrane that would otherwise cross by simple diffusion.

Osmosis

The diffusion of water across a selectively permeable membrane.

Hypertonic Solution

A solution with a higher solute concentration than that inside the cell, causing the cell to lose water.

Hypotonic Solution

A solution with a lower solute concentration than that inside the cell, causing the cell to gain water.

Isotonic Solution

A solution with the same solute concentration as that inside the cell, resulting in no net water movement.

Active Transport

The movement of substances against their concentration gradient, requiring energy, usually in the form of ATP.

Sodium-Potassium Pump

An important active transport system that moves Na+ out of the cell and K+ into the cell against their concentration gradients.

Phagocytosis

A type of endocytosis where the cell engulfs large particles or cells.

Pinocytosis

A type of endocytosis where the cell ingests extracellular fluid and small molecules.

Receptor-mediated Endocytosis

A process where the binding of ligands to receptors triggers vesicle formation for substance uptake.

Aquaporin

A type of channel protein that facilitates the rapid transport of water across cell membranes.

Turgor Pressure

The pressure exerted by the fluid in a vacuole against the cell wall of a plant cell.

Desaturase

An enzyme that catalyzes the formation of double bonds in fatty acids, promoting membrane fluidity.

Cholesterol

A steroid that maintains membrane fluidity and integrity at different temperatures.

Glycolipids

Carbohydrates covalently bonded to lipids, often found on the outer surface of the plasma membrane for cell recognition.

Glycoproteins

Carbohydrates covalently bonded to proteins, important for cell-cell recognition and signaling.

Integral Proteins

Proteins that penetrate the hydrophobic interior of the lipid bilayer, often spanning the entire membrane.

Peripheral Proteins

Proteins loosely bound to the surface of the membrane or