Centromere

Definition

The centromere is a specialized region of a chromosome that plays a crucial role in cell division by serving as the attachment point for spindle fibers during mitosis and meiosis. It ensures the proper segregation of sister chromatids into daughter cells, maintaining genetic stability. The structure of the centromere includes repetitive DNA sequences and is essential for the formation of the kinetochore, which facilitates the movement of chromosomes.

5 Must Know Facts For Your Next Test

1. The centromere is crucial for accurate chromosome segregation, preventing errors that could lead to genetic disorders.
2. In humans, centromeres are often characterized by long stretches of repetitive DNA sequences known as satellite DNA.
3. During cell division, microtubules from the spindle apparatus attach to the kinetochore formed at the centromere.
4. Different chromosomes can have different types of centromeres, categorized into metacentric, submetacentric, acrocentric, and telocentric based on their position.
5. Errors in centromere function or structure can lead to chromosomal abnormalities such as aneuploidy, which is linked to various diseases including cancer.

Review Questions

• How does the structure of the centromere contribute to its function during cell division?
  • The structure of the centromere is designed to facilitate its function during cell division. It is composed of repetitive DNA sequences that create a unique region on the chromosome, allowing for the formation of the kinetochore. The kinetochore serves as the binding site for spindle fibers, ensuring that sister chromatids are accurately pulled apart and segregated into daughter cells. This structural design is critical for maintaining genetic stability during cell division.
• What role do centromeres play in preventing genetic disorders related to chromosome segregation errors?
  • Centromeres play a vital role in preventing genetic disorders by ensuring proper chromosome segregation during mitosis and meiosis. If centromeres malfunction or are structurally compromised, it can lead to incorrect attachment of spindle fibers to chromosomes, causing missegregation. This missegregation can result in aneuploidy, where cells have an abnormal number of chromosomes, which is linked to various genetic disorders and conditions such as Down syndrome and certain cancers.
• Evaluate how variations in centromere structure across different chromosomes might influence their behavior during cell division.
  • Variations in centromere structure across different chromosomes can significantly influence their behavior during cell division. For instance, metacentric chromosomes have centrally located centromeres that result in equal arms, while acrocentric chromosomes have off-center centromeres that produce unequal arms. These structural differences can affect how spindle fibers attach and pull on the chromosomes, potentially leading to varying rates of segregation errors. Understanding these variations helps researchers predict behaviors associated with chromosomal stability and susceptibility to diseases linked to missegregation.

Related terms

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

chromatid: One of the two identical halves of a duplicated chromosome, which are joined together at the centromere before being separated during cell division.

aneuploidy:

A condition in which cells have an abnormal number of chromosomes, often resulting from errors in chromosome segregation at the centromere.