Principles of Biology Chapter 4 Terms

Plasma Membrane

membrane surrounding the cytoplasm that consists of a phospholipid bilayer with embedded proteins; functions to regulate the entrance and exit of molecules to and from the cell

Homeostasis

maintenance of normal internal conditions in a cell or an organism by means of self-regulating mechanisms

Fluid-Mosaic Model

model for the plasma membrane based on the changing location and pattern of protein molecules in a fluid phospholipid bilayer

Glycolipid

lipid in plasma membranes that contains an attached carbohydrate chain; assembles in the Golgi apparatus

Glycoprotein

protein in plasma membranes that has an attached carbohydrate chain; assembled in the Golgi apparatus

Channel Protien

protein that forms a channel to allow a particular molecule or ion to cross the plasma membrane

Carrier Protein

protein in the plasma membrane that combines with and transports a molecule or ion across the plasma membrane C

Cell Recognition Protiens

glycoproteins in the plasma membrane that identify self and help the body defend itself against pathogens

Receptor Protiens

protein located in the plasma membrane or within the cell; inds to a substance that alters some metabolic aspect of the cell

Enzymatic Protien

protein that catalyzes a specific reaction, may be found in the plasma membrane or the cytoplasm of the cell

Selectively Permeable

property of the plasma membrane that allows some substances to pass, but prohibits the movement of others

Diffusion

movement of molecules or ions from a region of higher to lower concentration; it requires no energy and tends to lead to an equal distribution (equilibrium)

Solute

substance that is dissolved in a solvent, forming a solution

Solvent

liquid portion of a solution that serves to dissolve a solute

Osmosis

diffusion of water through a selectively permeable membrane

Osmotic Pressure

measure of the tendency of water to move across a selectively permeable membrane; visible as an increase in liquid on the side of the membrane with higher solute concentration

Isotonic Solution

solution that is equal in solute concentration to that of the cytoplasm if a cell; causes cell to neither lose nor gain water by osmosis

Hypotonic Solution

solution that contains a lower solute (more water) concentration than the cytoplasm of a cell; causes cell to gain water by osmosis

Hypertonic Solution

higher solute concentration (less water) than the cytoplasm of a cell; causes cell to lose water by osmosis

Facilitated Transport

passive transfer of a substance into or out of a cell along a concentration gradiet by a process that requires a protien carrier

Active Transport

use of a plasma membrane carrier protein to move a muscle or ion from a region of lower concentration to one of higher concentration; it opposes equilibrium and requires energy

Exocytosis

process in which an intracellular vesicle fuses with the plasma membrane so that the vesicles contents are released outside the cell

Endocytosis

process by which substances are moved into the cell from the environment; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis

Phagocytosis

process by which cells engulf large substances, forming an intracellular vacuole

Pinocytosis

process by which vesicle formation brings macromolecules into the cell

Receptor Mediated Endocytosis

selective uptake of molecules into a cell by vacuole formation after they bind to specific receptor proteins in the plasma membrane