Cell Membrane & Cell Transport

Phospholipid

a lipid containing a phosphate group in its molecule.

Hydrophilic

attracted to water.

Hydrophobic

repelled by water.

Phospholipid Bilayer

a two-layered arrangement of phosphate and lipid molecules that form a cell membrane.

Selectively Permeable

a property of cell membranes that only allows certain molecules to enter or exit the cell.

Cholesterol

a lipid that regulates the fluidity of the membrane and gives mechanical stability.

Glycoprotein

a protein with carbohydrates attached that identifies the cell type.

Receptor Protein

a protein that recognizes and binds with substances outside the cell.

Transport Protein

a protein that provides a way for large or charged molecules to cross the membrane.

Fluid Mosaic Model

a model that describes the cell membrane as a tapestry of several types of molecules that are constantly moving.

Passive Transport

the movement of substances across a cell membrane without the use of energy.

Diffusion

the movement of molecules from an area of high concentration to an area of low concentration.

Osmosis

the diffusion of water across a selectively permeable membrane.

Facilitated Diffusion

the movement of specific molecules across cell membranes through protein channels.

Active Transport

the movement of materials from an area of low concentration to an area of high concentration using energy.

Sodium-Potassium Pump

a transport protein that pumps sodium ions out and potassium ions into the cell.

Endocytosis

the process by which a cell takes in large particles by engulfing them.

Exocytosis

the process by which a cell expels large materials.

Hypertonic Solution

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

Hypotonic Solution

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

Isotonic Solution

a solution with the same solute concentration as another solution.

Cytolysis

the bursting of a cell due to excess water intake.

Plasmolysis

the shrinking of a cell due to water loss.

Aquaporin

a water channel protein in the cell membrane.