Cell Membrane

Cell Membrane

A barrier that separates the internal environment of the cell from the external environment.

Selectively Permeable

A property of cell membranes that allows some substances to pass while blocking others.

Fluid Mosaic Model

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

Diffusion

The movement of particles from an area of low concentration to an area of high concentration.

Osmosis

The movement of water from a region of lower water concentration to a region of higher water concentration through a selectively permeable membrane.

Isotonic Solution

A solution with the same concentration of solute as another solution, resulting in no net movement of water.

Hypertonic Solution

A solution with a higher concentration of solute than another solution, leading to water leaving the cell and causing it to shrink.

Hypotonic Solution

A solution with a lower concentration of solute than another solution, resulting in water entering the cell and possibly causing it to burst.

Facilitated Transport

A process of passive transport that uses protein carriers to move molecules across a membrane without energy.

Active Transport

The movement of molecules against their concentration gradient, requiring energy (ATP) to move particles from areas of lower concentration to higher concentration.

Endocytosis

The process by which a cell takes in large particles or molecules by engulfing them in a vesicle.

Exocytosis

The process where a cell expels materials in vesicles that fuse with the cell membrane.

Crenation

The process of cell shrinking due to water loss when in a hypertonic solution.

Turgor Pressure

The pressure exerted by water inside the cell against the cell wall, important for maintaining plant cell shape.