Cell: The smallest basic unit from which all living organisms are built; the structural and functional building block of life.
Cell structure: The arrangement of the different parts that make up a cell, such as the membrane, cytoplasm and nucleus.
Organelle: A small specialised structure inside a cell that carries out a particular job, for example a mitochondrion or chloroplast.
Animal cell: A type of cell that contains a cell membrane, cytoplasm, nucleus, ribosomes and mitochondria but has no cell wall, chloroplasts or large permanent vacuole.
Plant cell: A type of cell that has all the parts of an animal cell plus a cellulose cell wall, chloroplasts and a large permanent vacuole filled with cell sap.
Bacterial cell: A single-celled prokaryotic organism made of a cell wall, cell membrane, cytoplasm, ribosomes, circular DNA and sometimes plasmids, with no nucleus or membrane-bound organelles.
Cell membrane: The thin outer layer surrounding the cytoplasm of all cells that controls which substances pass into and out of the cell; also called the surface membrane.
Cell wall: A rigid outer layer made mainly of cellulose found in plant cells; it supports the cell, gives it a fixed shape and stops it bursting when full of water.