Cell Signaling Practice Test 2025 - Free Cell Signaling Practice Questions and Study Guide

The structure at the centromere responsible for the attachment of spindle fibers is called the kinetochore. The kinetochore is a protein complex that assembles on the centromere of each chromosome during cell division. It plays a crucial role in ensuring that sister chromatids are properly segregated to opposite poles of the cell during mitosis and meiosis.

During cell division, the spindle fibers extend from the centrosomes and attach to the kinetochores. This binding is essential for the movement of chromosomes, as the spindle apparatus pulls the chromatids apart toward the poles. The kinetochore not only serves as the attachment point for spindle fibers but also helps in the regulation of the process, ensuring accurate separation and maintenance of genetic stability.

In contrast, other structures mentioned do not serve this function: the centrosome is the microtubule-organizing center that helps in the formation of the spindle apparatus; chromatids refer to the individual strands of a duplicated chromosome; and telomeres are the protective caps at the ends of chromosomes that prevent deterioration or fusion with neighboring chromosomes. Thus, the kinetochore is specifically critical for the attachment of spindle fibers, facilitating effective chromosome movement during cell division.