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 anaction 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
Chapter 3 Cell Structure and Function

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