PASSIVE TRANSPORT

passive transport

Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

semipermeable membrane

A membrane that allows some molecules to pass through but does not allow other molecules to pass through

phospholipid bilayer

Molecules that are constituents of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

diffusion

Movement of solutes from an area of higher concentration to an area of lower concentration to reach equilibrium

osmosis

Diffusion of water across a membrane

facilitated diffusion

Another type of passive transport, used for molecules that cannot diffuse through cell membranes usually becuase of their shape and/or size.

concentration gradient

A difference in the "amount" of a substance across a distance.

hypertonic

Having a higher concentration of solutes than another solution.

hypotonic

Having a lower concentration of solutes than another solution.

isotonic

Two solutions having equal solute concentrations

equilibrium

A state of balance among the components of a system.

Brownian Motion

Atoms, molecules, and particles are always moving in random directions; randomly moving particles that hit each other move in opposite directions

extracellular

environment outside the cell (usually referred to as the blood stream)

intracellular

environment inside the cell

hydrophobic

"water hating"

hydrophillic

"water-loving"

tonicity

Describes the ability of a solution to cause a cell to gain or lose water (ex: hyper, hypo, iso)

polar

a molucule that has charged ends

nonpolar

a molecule that does not have sharged ends. It is inert (ex: fat, oil)

ATP

Main energy molecule used in cells to do work

Fluid Mosaic Model

Describes the arrangement of phospholipids and proteins in biological membranes. Many parts come together to form the whole.

plasmolysis

A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment.

lysis

- swelling of cells that eventually bursts