Cell (biology)

The cell is the basic structural and functional unit of all <a href="/facts/Life/DNw7NUId">forms of life</a>. Every cell consists of <a href="/facts/Cytoplasm/Wa0sE6xf">cytoplasm</a> enclosed within a <a href="/facts/Cell_membrane/vAXSD0DT">membrane</a>; many cells contain <a href="/facts/Organelle/vhDFnGbs">organelles</a>, each with a specific function. The term comes from the <a href="/facts/Latin/pM3Kge85">Latin</a> word cellula meaning 'small room'. Most cells are only visible under a <a href="/facts/Light_microscope/5700vcna">microscope</a>. Cells <a href="/facts/Abiogenesis/BvAmLPQP">emerged on Earth</a> about 4 billion years ago. All cells are capable of <a href="/facts/Self-replication/NbsfzT4l">replication</a>, <a href="/facts/Protein_synthesis/P4IcGjPd">protein synthesis</a>, and <a href="/facts/Cell_motility/5ySAMquQ">motility</a>. 
Cells are broadly categorized into two types: <a href="/facts/Eukaryotic_cell/SkwyPLMA">eukaryotic cells</a>, which possess a <a href="/facts/Cell_nucleus/D7sFRa3c">nucleus</a>, and <a href="/facts/Prokaryotic/oYyvaDDH">prokaryotic cells</a>, which lack a nucleus but have a nucleoid region. Prokaryotes are <a href="/facts/Single-celled_organism/9PQsRuHU">single-celled organisms</a> such as <a href="/facts/Bacteria/wC8xSCsU">bacteria</a>, whereas eukaryotes can be either single-celled, such as <a href="/facts/Amoeba/xxvUal7B">amoebae</a>, or <a href="/facts/Multicellular_organism/rk8QBF7o">multicellular</a>, such as some <a href="/facts/Algae/U1ftVKU3">algae</a>, <a href="/facts/Plant/X5BMDMvS">plants</a>, <a href="/facts/Animal/4b8J33nd">animals</a>, and <a href="/facts/Fungi/BHo5DP59">fungi</a>. Eukaryotic cells contain organelles including <a href="/facts/Mitochondrion/ErHqrdJ1">mitochondria</a>, which provide energy for cell functions, <a href="/facts/Chloroplast/fo8U3yTx">chloroplasts</a>, which in plants create sugars by <a href="/facts/Photosynthesis/TMV7w693">photosynthesis</a>, and <a href="/facts/Ribosome/CF2u2gtg">ribosomes</a>, which synthesise proteins.
Cells were discovered by <a href="/facts/Robert_Hooke/T5sEElp5">Robert Hooke</a> in 1665, who named them after their resemblance to <a href="/facts/Monastic_cell/5WoImRk3">cells</a> inhabited by <a href="/facts/Christian_monasticism/yWkNNrns">Christian monks</a> in a monastery. <a href="/facts/Cell_theory/71xtwL7f">Cell theory</a>, developed in 1839 by <a href="/facts/Matthias_Jakob_Schleiden/UvKv4hBV">Matthias Jakob Schleiden</a> and <a href="/facts/Theodor_Schwann/zG3Cb08t">Theodor Schwann</a>, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells.

Cell (biology) open-in-new

Cell (biology)