Final answer:
Securin is the protein that is tagged by ubiquitin for degradation, allowing sister chromatids to separate during anaphase of cell division.
Step-by-step explanation:
The protein that is tagged by ubiquitin for degradation in regards to the separation of chromosomes is securin. During the process of cell division, securin is marked for destruction which allows the enzyme separase to cleave the cohesin proteins holding the sister chromatids together. Once cohesin is cleaved, the sister chromatids can separate, which is an essential step during anaphase of mitosis and meiosis II.
In the broader context of cell cycle regulation, degradation of specific proteins via ubiquitin tagging is crucial for the proper progression and timing of cell division. For instance, the degradation of cyclins, a different set of regulatory proteins, also occurs through ubiquitination, contributing to the control of other phases of the cell cycle. Ubiquitin acts as a signal for targeted proteins to be sent to the proteasome, where they are subsequently degraded.