Cell

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Cell The basic unit of plant and animal bodies; it comprises, at least, a nucleus or nuclear material and cytoplasm enclosed within a cell membrane. Many cells contain other specialized structures (organelles), such as mitochondria, chloroplasts, Golgi bodies, and flagella. Many simple organisms comprise a single cell, and may lack a membrane separating nuclear material from cytoplasm. Advanced organisms consist of a variety of co-operating cells, often specialized to perform particular functions and organized into tissues and organs. Plant cells are typically surrounded by an outer cell wall containing cellulose. Cell division may occur by splitting into two parts (fission), by mitosis, and (in the case of reproductive cells) by meiosis. All nucleated cells contain within their nuclei the entire inherited genetic information of that individual, but in specialized cells, such as a liver or brain cell, only a minute fraction of their genetic database is operational. >>

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