| A | B |
|---|
| lysosome | membrane-bound organelle that contains various hydrolytic enzymes |
| cytoskeleton | internal structure of cytoplasm; made of microfilaments and microtubules |
| microtubule | hollow, spiral assembly of protein molecules that composes flagella, cilia, mitotic spindles, and other cellular structures |
| centrosome | area near the nucleus of a cell that functions in the production of microtubules |
| microfilament | flexible, rodlike assembly of protein molecules found in cells |
| flagellum | long tubular extension of a cell's membrane that aids in movement |
| cilium | one of the numerous short extensions of a cell membrane; aids in movement |
| plastid | membrane-bound organelle found in plants, algae, and a few other organisms, but not in animals |
| chloroplast | organelle that contains chlorophyll for photosynthesis |
| vacuole | membrane-bound organelle in a cell; stores materials |
| vesicle | a small vacuole |
| turgor pressure | added pressure within a plant cell that results from the movement of water into the central vacuole |
| nucleus | positively charged central portion of an atom. |
| nuclear envelope | double membrane forming the surface of the nucleus in eukaryotic cells |
| chromatin material | complex of DNA and surrounding proteins in the nucleus of a cell |
| nucleolous | spherical body in the nuceus that has a high concentration of RNA and proteins |
| homeostasis | equilibrium or interal "steady state" that every living organism must maintain |
| isotonic solution | solution that has the same concentration of solutes as the cytoplasm of living cells |
| hypotonic solution | solution in which the concentration of solutes is less that in the cytoplasm of living cells |
| hypertonic solution | solution in which the concentration of solutes is greater than in the cytoplasm of living cells |
| passive transport | movement of substances through a cellular membrane without the expenditure of cellular energy |
| facilitated diffusion | passive transport that requires the presence of a protein factor in the cellular membrane |
| transport protein | protein molecule embedded in the cell membrane that mediates the passage of certain molecules |
| active transport | movement of molecules across cellular membranes against the concentration gradient; requires cellular energy expenditure |
| endocytosis | movement of materials across a cell's membrane and into the cell by phagocytosis or pinocytosis |
| phagocytosis | process of a cell engulfing a substance |
| pinocytosis | process whereby a cell takes in fluid by forming vesicles |
| exocytosis | process in which vaculoles or vesicles fuse with the cell membrane to release particles or substances from the cell |
