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The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope.
Cells are the basic unit of structure in all living organisms and also the basic unit of reproduction. Cell theory has traditionally been accepted as the governing theory of all life, [1] but some biologists consider non-cellular entities such as viruses living organisms [2] and thus disagree with the universal application of cell theory to all ...
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. [1] [2] All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. [3] Cell biology is the study of the structural and functional ...
Cell theory states that cells are the fundamental units of life, that all living things are composed of one or more cells, and that all cells arise from preexisting cells through cell division. [41] Most cells are very small, with diameters ranging from 1 to 100 micrometers and are therefore only visible under a light or electron microscope. [42]
The cell is the structural and functional unit of life. Smaller organisms, including prokaryotes (bacteria and archaea), consist of small single cells. Larger organisms, mainly eukaryotes, can consist of single cells or may be multicellular with more complex structure. Life is only known to exist on Earth but extraterrestrial life is thought ...
Cell: Basic unit of all life and the grouping of organelles Super-cellular level (Multicellular level) Tissue: Functional groups of cells Organ: Functional groups of tissues Organ system: Functional groups of organs Ecological levels: Organism: The basic living system, a functional grouping of the lower-level components, including at least one ...
Light micrograph of a moss's leaf cells at 400X magnification. The following outline is provided as an overview of and topical guide to cell biology: . Cell biology – A branch of biology that includes study of cells regarding their physiological properties, structure, and function; the organelles they contain; interactions with their environment; and their life cycle, division, and death.
Basic biochemical principles imply that all organisms do have a common ancestry. [71] A proposed, earlier, non-cellular ancestor to LUCA is the First universal common ancestor (FUCA). [72] [73] FUCA would therefore be the ancestor to every modern cell as well as ancient, now-extinct cellular lineages not descendant of LUCA. FUCA is assumed to ...