mitotic spindle

Kinetochores are large protein complexes that are formed on chromosome regions known as centromeres. For high-fidelity chromosome segregation, kinetochores must be correctly captured on the mitotic spindle before anaphase onset.

During prometaphase, kinetochores are initially captured by a single microtubule that extends from a spindle pole and are then transported poleward along the microtubule.

Subsequently, microtubules that extend from the other spindle pole also interact with kinetochores and, eventually, each sister kinetochore attaches to microtubules that extend from opposite poles - this is known as bi-orientation.

The spindle assembly checkpoint (SAC) ensures the fidelity of chromosome segregation by preventing cell-cycle progression until all the chromosomes make proper bipolar attachments to the mitotic spindle and come under tension.

See also

 mitosis

References

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