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33 terms

Biology Chapter 6

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cell theory
generalization that all living things are composed of cells, and that cells are the basic unit of structure and function in living things
micrograph
photograph of the view through a microscope
organelle
part of a cell with a specific function
plasma membrane
thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings
cytoplasm
region of a cell between the nucleus and the plasma membrane
eukaryotic cell
cell with a nucleus (surrounded by its own membrane) and other internal organelles
phospholipid bilayer
two layer "sandwich" of molecules that surrounds a cell
diffusion
new movements of the particles of a substance from where they are more concentrated to where they are less concentrated
equilibrium
point at which the number of diffusing molecules moving in one direction is equal to the number of moving in the opposite direction
selectively permeable membrane
membrane that allows some substances to pass more easily than others and blocks the passage of some substances altogether
passive transport
diffusion across a membrane requiring only the random motion of molecules with no energy expended by the cell
facilitated diffusion
pathway provided by transport proteins that helps certain molecules pass through a membrane
hypotonic
having a lower concentration of solute than another solution
hypertonic
having a higher concentration of solute than another solution
osmoisis
passive transport of water across a selectively permeable membrane
active transport
movement of molecules across a membrane requiring energy to be expended by the cell
vesicles
small membrane-bound sac that functions in moving products into, out of, and within a cell
exocytosis
process of exporting proteins from a cell by a vesicle fusing with the plasma membrane
endocytosis
process of taking material into a cell within vesicles that bud inward from the plasma membrane
nuclear envelope
double membrane that surrounds a cell nucleus
nucleolus
ball-like mass of fibers and granules in a cell nucleus
ribosomes
cluster of proteins and nucleic acids that constructs proteins in a cell
endoplasmic reticulum
network of membranes within a cell's cytoplasm that produce a variety of molecules
Golgi apparatus
cellular organelle that modifies, stores, and routes cell products
vacuoles
membrane-bound sac that buds from the endoplasmic reticulum or the Golgi apparatus
lysosomes
membrane-bound sac containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides
chloroplasts
organelle found in some plant cells and certain unicellular organisms where photosynthesis takes place
mitochondria
cellular organelles where cellular respiration occurs
ATP
(adenosine triphosphate) main energy source that cells use for most of their work
microtubules
straight, hollow tube of proteins that gives rigidity, shape, and organization to a cell
microfilaments
solid rod of protein, thinner than a microtubule, that enables a cell to move or change shape
flagella
long, thin, whip-like structure, with a core of microtubules, that enable some cells to move
cilia
short structures containing bundles of microtubules that move a cell through its surroundings or move fluid over the cell's surface