Plasma membrane

Plasma membrane

A biological membrane that separates and protects the cell's internal environment from the external environment.

Phospholipid bilayer

A double layer of phospholipids that makes up the cell membrane, with hydrophilic heads facing outward and hydrophobic tails facing inward.

Amphipathic

A molecule that has both a hydrophilic (water-loving) and a hydrophobic (water-fearing) part.

Integral protein

A protein that is embedded in the lipid bilayer, often spanning the membrane and involved in transport.

Peripheral protein

A protein that is attached to the outer or inner surface of the lipid bilayer and not embedded.

Channel protein

A type of integral protein that forms a passageway for specific molecules to cross the membrane.

Hormone receptor

A protein that binds with specific hormones to trigger a response in the cell.

Glycoprotein

A molecule consisting of a protein and a carbohydrate; involved in cell recognition and signaling.

Immobilized enzyme

An enzyme that is fixed in position in a membrane and available for substrate interaction.

Protein pump

A type of integral protein that uses ATP to transport ions or molecules against their concentration gradient.

Cell adhesion protein

A protein that helps cells stick to one another to form tissues.

Fluid mosaic model

A model that describes the structure of cell membranes as a mosaic of various proteins that float in or on the fluid lipid bilayer.

Passive transport

The movement of molecules across the membrane without the use of energy.

Active transport

The movement of molecules across a membrane requiring energy, typically against a concentration gradient.

Simple diffusion

The process by which small or nonpolar molecules pass through the plasma membrane without assistance.

Facilitated diffusion

The process of transporting molecules across a membrane via proteins, without the use of energy.

Osmosis

The diffusion of water across a selectively permeable membrane.

Hypotonic

A solution with a lower solute concentration compared to another solution.

Isotonic

A solution with equal solute concentration compared to another solution.

Hypertonic

A solution with a higher solute concentration compared to another solution.

Selectively permeable membrane

A membrane that allows certain substances to pass while restricting others.

Solvability differences

Variations in the ability of different substances to dissolve in a solvent, which affects their movement in biological systems.