Functions of the Cell Membrane

Hydrophobic

"Water-fearing"; pertaining to nonpolar molecules (or parts of molecules) that do not dissolve in water.

Hydrophilic

"water-loving"; pertaining to polar or charged molecules (or parts of molecules) that are soluble in water

Equilibrium

A state of balance among the components of a system (homeostasis).

Cholesterol

A steroid that is an important component of animal cell membranes and that acts as a precursor molecule for the synthesis of other steroids such as hormones.

Hypertonic

Having a higher concentration of solute than another solution.

Cell Membrane

A cell structure that controls which substances can enter or leave the cell.

Phospholipid Bilayer

A double layer of phospholipids that makes up plasma and organelle membranes

Selectively Permeable/Semi-Permeable

A feature and a function of the plasma membrane that is essential to maintain homeostasis by regulating the passage of some substances while preventing others from entering the cell.

Concentration

A measurement of how much solute exists within a certain volume of solvent

Fluid Mosaic Model

Membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a bilayer of phospholipids.

Protein channel

proteins that provide passageways through the membrane for certain hydrophilic (water-soluble) substances such as polar and charged molecules

Hypotonic

Having a lower concentration of solute than another solution

Plasmolysis

As a plant cell loses water, it shrivels, and its plasma membrane pulls away from the cell wall

Cytolysis

Bursting of a cell

Isotonic

Describes a solution whose solute concentration is equal to the solute concentration inside a cell

Osmosis

Diffusion of water through a selectively permeable membrane

Passive Transport

Movement across the cell membrane that does not require energy from the cell

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Facilitated Diffusion

Movement of specific molecules across cell membranes through protein channels.

Turgor Pressure

Pressure that water molecules exert against the cell wall

Receptor Molecule

Proteins that transmit information in and out of cells. They allow communication between cells., Proteins on the surface of the cell membrane that receive signals from the nervous and endocrine system. These are needed for your cells to communicate and work together.

Active Transport

The energy-requiring movement of substances across a biological membrane against a concentration gradient