Term | Definition |
cell theory | theory that states that all organisms are made of cells, all existing cells are produced by living things, and the cell is the most basic unit of life |
cytoplasm | a jellylike substance inside cells that contains molecules and in some cells organelles |
organelles | membrane-bound structure that is specialized to perform a distinct process within a cell |
prokaryotic cells | cell that does not have a nucleus or other membrane-bound organelles |
eukaryotic cells | cell that has a nucleus and other membrane-bound organelles |
cytoskeleton | network of proteins, such as microtubules and microfilaments, inside a eukaryotic cell that supports and shapes the cell |
nucleus | organelle composed of a double membrane that acts as the storehouse for most of a cell’s DNA |
endoplasmic reticulum | interconnected network of thin, folded membranes that
produce, process, and distribute proteins |
ribosomes | organelle that links amino acids together to form proteins |
Golgi apparatus | stack of flat, membrane-enclosed spaces containing enzymes that process, sort, and deliver proteins |
vesicles | small organelle that contains and transports materials within the cytoplasm |
mitochondria | bean-shaped organelle that supplies energy to the cell and has its own ribosomes and DNA |
vacuole | organelle that is used to store materials, such as water, food, or enzymes, that are needed by the cell |
lysosomes | organelle that contains enzymes |
centrioles | cylinder-shaped organelles made of short microtubules arranged in a circle |
cell wall | a rigid layer that gives protection, support, and shape to the cell |
chloroplasts | organelles that carry out photosynthesis, a series of complex chemical reactions that convert solar energy into energy-rich molecules the cell can use |
cell membrane | forms a boundary between a cell and the outside environment and controls the passage of materials into and out of a cell |
phospholipid | a molecule composed of 3 basic parts: a charged phosphate group, glycerol, and two fatty acid chains |
fluid mosaic model | model that describes the arrangement and movement of the molecules that make up a cell membrane |
selective permeability | condition or quality of allowing some, but not all, materials to cross a barrier or membrane |
receptor | protein that detects a signal molecule and performs an
action in response |
passive transport | the movement of molecules across a cell membrane without energy input from cells |
diffusion | movement of dissolved molecules in a fluid or gas from a region of higher concentration to a region of lower concentration |
concentration gradient | the difference in the concentration of a substance from one location to another |
osmosis | diffusion of water molecules across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration |
isotonic | solution that has an equal concentration of dissolved particles compared with another solution |
hypertonic | solution that has a higher concentration of dissolved particles compared with another solution |
hypotonic | solution that has a lower concentration of dissolved particles compared with another solution |
facilitated diffusion | diffusion of molecules assisted by protein channels that pierce a cell membrane |
active transport | energy-requiring movement of molecules across a membrane from a region of lower concentration to a region of higher concentration |
endocytosis | the process of taking liquids or fairly large molecules into a cell by engulfing them in a membrane |
phagocytosis | uptake of a solid particle into a cell by engulfing the particle; see endocytosis |
exocytosis | the release of substances out a cell by the fusion of a vesicle with the membrane |