What are the protein threads produced during mitosis that help pull chromatids apart called?

During mitosis, the protein threads that are crucial for pulling chromatids apart are known as spindle fibres. These structures are composed of microtubules, which are protein polymers that play an essential role in cell division. The spindle fibres emanate from the centrosomes and attach to the centromeres of the chromosomes during metaphase.

As the cell progresses into anaphase, the spindle fibres shorten, creating the force necessary to separate the sister chromatids and pull them toward opposite poles of the cell. This is a critical step in ensuring that each daughter cell receives an identical set of chromosomes.

The other terms, while related to the cellular structure, do not accurately describe these specific protein threads involved in mitosis. Microtubules are the components that make up the spindle fibres, but the term spindle fibres specifically refers to the arrangement and function of these microtubules during mitosis. Filaments could refer to various types of protein structures in cells but are not specific to the context of chromosome separation. Centrioles are cellular structures that help organize the spindle fibres but are not the threads themselves; rather, they serve as anchoring points for the spindle apparatus.