Cell Transport Vocabulary

Essential Vocabulary:

passive transport- diffusion across a plasma membrane in which the cell expends no energy, the energy for this movement comes from random molecular energy (kinetic energy)

active transport- transport of molecules against a concentration gradient (from regions of low concentration to regions of high concentration) with the aid of proteins in the cell membrane and energy from ATP

diffusion - the spontaneous movement of particles from an area of higher concentration to an area of lower concentration, the energy for this movement comes from random molecular energy (kinetic energy)

osmosis- diffusion of water molecules across a membrane in response to differences in solute concentration. Water moves from areas of high-water/low-solute concentration to areas of low-water/high-solute concentration. Diffusion of water across a semi-permeable barrier such as a cell membrane, from high water potential to lower water potential

homeostasis- the ability to maintain a relatively constant internal environment while responding to the external environment

cell membrane- the semipermeable membrane that encloses the cytoplasm of a cell, also called plasma membrane

lipids- the class of organic macromolecules that functions in the long-term storage of biochemical energy, insulation, structure and control;ex.fats, waxes, oils and steroids

endocytosis- the incorporation of materials from outside the cell by the formation of vesicles in the plasma membrane that surround the material so the cell can engulf it

exocytosis- the process in which a membrane-enclosed vesicle first fuses with the plasma membrane and then opens and releases its contents to the outside

cell wall- structure produced by some cells outside their cell membrane; variously composed of chitin, peptidoglycan, or cellulose

cytoplasm- the viscous semiliquid inside the plasma membrane of a cell; contains various macromolecules and organelles in solution and suspension

permeable- can be penetrated, especially by liquids or gasses

semi-permeable- allows some substances to pass through while acting as a barrier against others

lipid bilayer- the foundational structure of plasma membranes composed of two layers of phospholipids positioned such that their polar hydrophilic heads face outward and their nonpolar hydrophobic tails are directed inward

hypotonic- a solution having a low concentration of solute or dissolved substances

hypertonic- a solution having a high concentration of solute or dissolved substances

isotonic- term applied to two solutions with equal solute concentrations

equilibrium- balance

concentration- the amount of a specified substance in a unit amount of another substance

gradient- a series of progressively increasing or decreasing differences in a cell

facilitated diffusion- the spontaneous passage of molecules or ions across a biological membrane passing through specific transmembrane transport proteins