Mitotic spindle

Definition

The mitotic spindle is a structure composed of microtubules that orchestrates the separation of chromosomes during cell division. It is essential for ensuring that each daughter cell receives an identical set of chromosomes, and its formation and function are tightly regulated during the phases of the cell cycle.

5 Must Know Facts For Your Next Test

1. The mitotic spindle is formed during prophase and disassembles during telophase, allowing for accurate chromosome segregation.
2. The spindle fibers attach to kinetochores, which are protein structures on the chromosomes that facilitate their movement during mitosis.
3. Proper functioning of the mitotic spindle is vital for preventing aneuploidy, a condition where cells have an abnormal number of chromosomes.
4. Spindle assembly checkpoint mechanisms ensure that all chromosomes are properly attached to the spindle before proceeding to anaphase.
5. Drugs such as taxol disrupt microtubule function and can inhibit spindle formation, which is a strategy used in cancer therapies.

Review Questions

• How does the mitotic spindle ensure accurate chromosome segregation during cell division?
  • The mitotic spindle ensures accurate chromosome segregation by forming attachments between spindle fibers and kinetochores on chromosomes. This connection allows the spindle to exert forces on each chromatid, pulling them apart to opposite poles of the cell during anaphase. The coordinated action of the spindle helps prevent errors, ensuring that each daughter cell receives an equal and complete set of chromosomes.
• Discuss the role of microtubules in the formation and function of the mitotic spindle.
  • Microtubules play a crucial role in both the formation and function of the mitotic spindle. They assemble from tubulin proteins at the centrosomes to create a framework that extends across the dividing cell. During mitosis, these microtubules dynamically grow and shrink, allowing them to capture chromosomes via kinetochores and guide them toward opposite poles. This dynamic instability is essential for proper spindle function and chromosome alignment.
• Evaluate how disruptions in mitotic spindle formation can contribute to cancer development.
  • Disruptions in mitotic spindle formation can lead to chromosomal instability, a hallmark of many cancers. If spindle assembly checkpoint mechanisms fail, it may result in incorrect attachment of chromosomes or premature separation, leading to aneuploidy. This abnormal distribution of chromosomes can create genetic diversity in tumor cells, enhancing their survival and proliferation while also complicating treatment efforts. Understanding these mechanisms is key to developing targeted therapies that address these cellular malfunctions.

Related terms

Microtubules: Dynamic filaments made of tubulin proteins that form part of the cytoskeleton, providing structural support and playing critical roles in cellular processes like transport and division.

Chromatid: One half of a duplicated chromosome, which is connected to its sister chromatid at the centromere until they are separated during mitosis.

Centrosome: An organelle that serves as the main microtubule organizing center of the cell, critical for the formation of the mitotic spindle during cell division.