31 terms

Chapter 5: The Working Cell

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energy
Ability to do work
kinetic energy
The energy of motion
potential energy
Energy that is stored and held in readiness
heat
Energy that is transformed as a consequence of temperature differences
entropy
a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.
chemical energy
Energy stored in chemical bonds
calorie
Amount of energy needed to raise temperature 1 gram of water 1 degree C
metabolism
A set of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes
ATP
(adenosine triphosphate) main energy source that cells use for most of their work
enzymes
Catalysts for chemical reactions in living things
active site
The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds.
substrate
A specific reactant acted upon by an enzyme
induced fit
The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate.
enzyme inhibitors
prevent substrate from binding with the active site by bonding with the enzyme and changing its shape or bonding to the enzyme's active site
feedback regulation
End product of a pathway inhibits an enzyme in the pathway.
transport proteins
A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.
diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration.
passive transport
Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient
facilitated diffusion
A process in which substances are transported across a plasma membrane with the concentration gradient with the aid of carrier (transport) proteins; does not require the use of energy.
osmosis
Diffusion of water through a selectively permeable membrane
hypertonic
Having a higher concentration of solute than another solution.
hypotonic
Having a lower concentration of solute than another solution
isotonic
Having the same solute concentration as another solution.
osmoregulation
The control of water balance in organisms living in hypertonic, hypotonic, or terrestrial environments.
active transport
The movement of particles from an area of low concentration to an area of high concentration that uses energy provided by ATP or a difference in electrical charges across a cell membrane.
exocytosis
a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.
endocytosis
Active transport process where a cell engulfs materials with a portion of the cell's plasma membrane and releases the contents inside of the cell.
phagocytosis
A type of endocytosis in which a cell engulfs large particles or whole cells
signal transduction pathways
The process by which a signal on a cell's surface is converted into a specific cellular response.
cell membrane
a thin, phospholipid bilayer, membrane around the cytoplasm of a cell that regulates what enters and exits the cell.
fluid mosaic model
The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.