Core Concepts
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Cell is the basic structural, functional and biological unit of life; all known cellular organisms are composed of one or more cells.
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The term cell is derived from the Latin cella, meaning small room.
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Cell biology / cytology is the branch of biology concerned with the structure, function, organisation and activities of cells.
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A typical cell contains cytoplasm enclosed by a plasma membrane; in eukaryotes, the genetic material is primarily housed inside a membrane-bound nucleus.
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Most plant and animal cells are microscopic, commonly ranging from roughly 1–100 μm in size, although cells show considerable variation.
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The human body contains tens of trillions of cells, with the exact estimate depending on the methodology and assumptions used.
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Cells perform essential life processes including:
- nutrition and metabolism;
- respiration and energy conversion;
- synthesis of biomolecules;
- growth;
- reproduction;
- response to stimuli;
- waste management;
- maintenance of internal conditions.