Centrosome

A centrosome is a cellular structure involved in cell division. Before division, the centrosome duplicates; as division begins, the two centrosomes move to opposite ends of the cell, and microtubules assemble into a spindle that helps separate replicated chromosomes into the daughter cells.

• In animal cells, the centrosome is the major microtubule-organizing center located adjacent to the nucleus; during mitosis, microtubules extend from duplicated centrosomes to form the mitotic spindle that separates chromosomes.
• The centrosome is duplicated during S phase; the two centrosomes give rise to the mitotic spindle.
• In animal cells, the centrosome contains a pair of centrioles that lie perpendicular to each other.

• If a prompt says a structure duplicates, moves to opposite poles, and a spindle forms between them -> <u>centrosomes</u>.
• If the question asks for the main microtubule-organizing center in animal cells -> <u>the centrosome</u>.
• If you see "pair of centrioles" mentioned as part of an organelle near the nucleus -> that organelle is the <u>centrosome</u>.