| A | B |
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| 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 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 (plural: nuclei) |
| endoplasmic reticulum | interconnected network of thin, folded membranes that produce, process, and distribute proteins |
| ribosome | organelle that links amino acids together to form proteins |
| Golgi apparatus | stack or flat, membrane-enclosed spaces containing enzymes that process, sort, and deliver proteins |
| vesicle | small organelle 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 (plural: mitochondria) |
| 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 a glycerol, a phosphate group, and two fatty acids |
| 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 | 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 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 compare with another solution |
| hypotonic | solution that has a lower concentration of dissolved particles compare 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 by inward folding of the cell membrane |
| phagocytosis | uptake of a solid particle into a cell by engulfing the particle |
| exocytosis | release of substance out of a cell by the fusion of a vesicle with the membrane |
