Centromere

Definition

A centromere is a specialized region of a chromosome that serves as the attachment point for spindle fibers during cell division. It plays a crucial role in the proper segregation of chromosomes into daughter cells, ensuring that each new cell receives the correct number of chromosomes. The centromere's structure also includes a unique DNA sequence and specific proteins that help regulate its function throughout the cell cycle.

5 Must Know Facts For Your Next Test

1. Centromeres are essential for the accurate distribution of chromosomes during both mitosis and meiosis.
2. The DNA sequence of centromeres is often repetitive and varies between species, which can complicate their identification.
3. Centromeres are characterized by the presence of specific histone proteins that form a structure known as the centromeric chromatin.
4. During cell division, the kinetochore forms at the centromere and is responsible for pulling apart sister chromatids to opposite poles of the cell.
5. Centromere function is regulated by various signaling pathways that ensure proper chromosome alignment and separation during the cell cycle.

Review Questions

• How does the structure of a centromere contribute to its function during cell division?
  • The structure of a centromere includes unique DNA sequences and specific proteins that facilitate the assembly of the kinetochore, which is essential for chromosome segregation. The repetitive nature of centromeric DNA helps in the formation of this specialized region, allowing spindle fibers to attach effectively. This interaction ensures that sister chromatids are pulled apart accurately, thus maintaining genetic stability in daughter cells.
• Discuss the role of kinetochores in relation to centromeres during mitosis.
  • Kinetochores are protein complexes that form at the centromeres during mitosis, serving as crucial sites for spindle fiber attachment. This connection allows the spindle apparatus to exert force on the chromosomes, facilitating their movement toward opposite poles of the dividing cell. Proper functioning of kinetochores at centromeres is vital for ensuring that each daughter cell receives an equal set of chromosomes, preventing errors such as aneuploidy.
• Evaluate the impact of defects in centromere function on cellular processes and organismal health.
  • Defects in centromere function can lead to serious consequences such as improper chromosome segregation, resulting in aneuploidy, which is linked to various diseases including cancer. When centromeres fail to operate correctly, it disrupts cellular homeostasis and can cause genetic imbalances that contribute to tumorigenesis or developmental disorders. Understanding these impacts highlights the importance of centromeres in maintaining genomic integrity and overall organismal health.

Related terms

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

Spindle Apparatus: A structure composed of microtubules that forms during cell division to help segregate chromosomes to the daughter cells.

Kinetochore:

A protein complex that assembles at the centromere during cell division and serves as the attachment site for spindle fibers.