biorientáció

Biorientáció is a term used in genetics and cell biology to describe the alignment of chromosomes during cell division. Specifically, it refers to the arrangement of sister chromatids at the metaphase plate of the spindle apparatus during mitosis and meiosis. Each sister chromatid is attached to microtubules originating from opposite poles of the cell. This attachment ensures that when the cell divides, each daughter cell receives an identical set of chromosomes.

During metaphase, the replicated chromosomes, each consisting of two identical sister chromatids, condense and become visible. They then align along the equatorial plane of the cell, known as the metaphase plate. The kinetochores, protein structures located at the centromeres of each chromatid, are crucial for biorientation. Microtubules from the spindle poles attach to these kinetochores. For proper biorientation, each sister chromatid must be attached to microtubules from opposite poles.

Failure of biorientation can lead to aneuploidy, a condition where cells have an abnormal number of chromosomes. This can occur if both sister chromatids are attached to microtubules from the same pole, or if one or both are not attached properly. Such errors can have significant consequences, including developmental abnormalities and cancer. The cell has sophisticated surveillance mechanisms, like the spindle assembly checkpoint, to detect and correct errors in biorientation before proceeding to anaphase, the stage where sister chromatids separate. Therefore, biorientation is a critical and tightly regulated process for maintaining genetic stability.