Term | Definition |
active transport | process that requires an expenditure of energy to move a substance across a cell membrane, usually moved against the concentration gradient |
apoptosis | the death of cells that occurs as a normal and controlled part of an organism's growth or development. |
cell membrane | the selectively permeable outer boundary of a cell consisting of a phospholipid bilayer embedded with proteins, plasma membrane or cytoplasmic membrane |
centrosome | cellular organelle consisting of two centrioles |
chromosome | rod-like structure that condenses from chromatin in a cell’s nucleus during mitosis |
cytoplasm | the contents of a cell, excluding the nucleus and cell membrane |
cytoskeleton | a microscopic network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence |
differentiation | cell specialization |
diffusion | random movement of molecules from a region of higher concentration toward one of lower concentration |
endocytosis | process by which a cell membrane envelops a substance and draws it into the cell in a vesicle |
endoplasmic reticulum | organelle composed of a system of connected membranous tubules and vesicles along which protein is synthesized |
equilibrium | a state of balance between two opposing forces |
exocytosis | transport of substances out of a cell in vesicles |
facilitated diffusion | diffusion in which carrier molecules transport substances across membranes from a region of higher concentration to a region of lower concentration |
filtration | movement of material through a membrane as a result of hydrostatic pressure |
Golgi apparatus | an organelle that prepares cellular products for secretion |
lysosome | organelle that contains digestive enzymes |
mitochondrion | organelle housing enzymes that catalyze reactions of aerobic respiration |
mitosis | diffusion of a somatic cell to form two genetically identical cells |
nucleolus | a small structure within the cell nucleus that contains RNA and proteins |
nucleus | a cellular organelle enclosed by a double-layered, porous membrane and containing DNA; the dense core of an atom composed of protons and neutrons |
organelle | a part of a cell that performs a specialized function |
osmosis | diffusion of water through a selectively permeable membrane in response to a concentration gradient |
phagocytosis | process by which a cell engulfs and digests solid substances |
pinocytosis | process by which a cell engulfs droplets of fluids from its surroundings |
ribosome | organelle composed of RNA and protein that is a structural support for protein synthesis |
selectively permeable | a membrane that allows some molecules through but not others; semipermeable |
vesicle | membranous cytoplasmic sac formed by infolding of the cell membrane |