<P> Before DNA replication, cells contain two centrioles . The older of the two centrioles is termed the mother centriole, the other the daughter . During the cell division cycle, a new centriole grows at the proximal end of both mother and daughter centrioles . After duplication, the two centriole pairs (freshly assembled centriole is now a daughter centriole in each pair) will remain attached to each other orthogonally until mitosis . At that point the mother and daughter centrioles separate dependently on an enzyme called separase . </P> <P> The two centrioles in the centrosome are tied to one another . The mother centriole has radiating appendages at the distal end of its long axis and is attached to its daughter at the proximal end . Each daughter cell formed after cell division will inherit one of these pairs . Centrioles start duplicating when DNA replicates . </P> <P> The last common ancestor of all eukaryotes was a ciliated cell with centrioles . Some lineages of eukaryotes, such as land plants, do not have centrioles except in their motile male gametes . Centrioles are completely absent from all cells of conifers and flowering plants, which do not have ciliate or flagellate gametes . It is unclear if the last common ancestor had one or two cilia . Important genes required for centriole growth, like centrins, are only found in eukaryotes and not in bacteria or archaeans . </P> <P> The word centriole (/ ˈsɛntrioʊl /) uses combining forms of centri - and - ole, yielding "little central part", which describes a centriole's typical location near the center of the cell . </P>

Where is the centriole located in a cell