Term | Definition |
cell theory | theory that states that all organisms are made of cells, all cells are produced by other living cells, and the cell is the most basic unit of life. |
cytoplasm | jellylike substance inside cells that contains molecules and in some cells organelles. |
organelle | membrane-bound structure that is specialized to perform a distinct process within a cell. |
prokaryotic cell | cell that does not have a nucleus or other membrane-bound organelles. |
eukaryotic cell | cell that has a nucleus and other membrane-bound organelles. |
cytoskeleton | network of proteins, such as microtubules and microfilaments, inside a eukaryotic cell and supports and shapes the cell. |
nucleus | organelle composed of a double membrane that acts as a storehouse for most of a cell's DNA. |
endoplasm reticulum | interconnected network of thin, folded membranes that produce, process, and distribute proteins. |
ribosome | organelle that links amino acids together to form a protein. |
Golgi apparatus | stack of flat, membrane-enclosed spaces containing enzymes that process, sort, and deliver proteins. |
vesicle | small organelles that contains and transports materials within the cytoplasm. |
mitochondrion | 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. |
lysosome | organelle that contains enzymes. |
centriole | small cylinder shaped organelle made of protein tubes arranged in a circle; aids mitosis. |
cell wall | rigid structure that gives protection, support, and shape to cells in plants, algae, fungi, and bacteria. |
chloroplast | organelle composed of numerous membranes that are used to convert solar energy into chemical energy: contains chlorophyll |
cell membrane | double-layer of phospholipids that forms a boundary between a cell and the surrounding environment and controls the passage of materials into and out of a cell. |
phospholipid | molecule that forms a double-layered cell membrane; consists of glycerol, a phosphate group, and two fatty acids. |
fluid mosaic model | model that describes the arrangement and movement of he 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 | movement of molecules across the cell membrane without energy input from the cell. |
diffusion | movement of dissolved molecules in a fluid or gas from a region of higher concentration to a region of lower concentration. |
concentration gradient | 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 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 | uptake of liquids or large molecules into a cell inward folding of the cell membrane. |
phagocytosis | uptake of a solid particle into a cell by engulfing the particle; see endocytosis |
exocytosis | release of substances out of a cell y the fusion of a vesicle with the membrane. |