Dicentric chromosomes

Definition

Dicentric chromosomes are chromosomal structures that possess two centromeres, resulting from the fusion of two chromosome fragments. These aberrations often arise due to exposure to ionizing radiation or other mutagens, and they can lead to unstable chromosome behavior during cell division. The presence of dicentric chromosomes is significant in biological dosimetry, where they serve as indicators of radiation exposure, and they also play a role in genomic instability, which can have various consequences for cellular health and cancer development.

5 Must Know Facts For Your Next Test

1. Dicentric chromosomes are often formed when two different chromosomes break and then rejoin incorrectly, each providing a centromere.
2. They are considered a sensitive marker for assessing prior radiation exposure in individuals due to their occurrence following high doses of ionizing radiation.
3. The presence of dicentric chromosomes can lead to aneuploidy during cell division, as the abnormal structure may not segregate properly.
4. Research indicates that the number of dicentric chromosomes can correlate with the dose of radiation received, making them useful in biological dosimetry.
5. Dicentric chromosomes contribute to genomic instability by increasing the likelihood of further chromosomal rearrangements and mutations over time.

Review Questions

• How do dicentric chromosomes form, and what implications do they have for cell division?
  • Dicentric chromosomes form when two chromosomal fragments that have lost their centromeres join together incorrectly, each fragment bringing a centromere. This abnormal structure complicates proper segregation during cell division, leading to potential aneuploidy, where cells have an abnormal number of chromosomes. As a result, dicentric chromosomes can cause further genomic instability and increase the risk of cancer development.
• Discuss the role of dicentric chromosomes in biological dosimetry and how they relate to radiation exposure assessment.
  • In biological dosimetry, dicentric chromosomes are used as biomarkers for assessing previous radiation exposure due to their formation after ionizing radiation. When individuals are exposed to high doses of radiation, the frequency of dicentric chromosomes in their lymphocytes can be measured. By quantifying these structures, researchers can estimate the dose received and evaluate potential health risks associated with that exposure.
• Evaluate the long-term effects of genomic instability caused by dicentric chromosomes on cancer development.
  • The long-term effects of genomic instability associated with dicentric chromosomes can significantly increase the risk of cancer. As cells with dicentric chromosomes undergo division, improper segregation can lead to further chromosomal rearrangements and mutations. This accumulation of genetic errors creates a favorable environment for malignant transformation, making individuals with high levels of dicentric chromosomes more susceptible to developing cancer over time.

Related terms

Chromosomal Aberrations: Alterations in chromosome structure or number, which can result from environmental factors, such as radiation, leading to various genetic consequences.

Genomic Instability:

A high frequency of mutations within the genome of a cellular lineage, which can lead to cancer and other diseases due to errors in DNA replication and repair.

Biological Dosimetry: A method used to estimate radiation exposure by analyzing biological samples for specific indicators, such as chromosomal aberrations.