Acentric chromosome

Acentric chromosome is a type of chromosome that lacks a centromere. The absence of a centromere, which is the region of a chromosome that separates it into a short arm (p) and a long arm (q), results in a chromosome that is unable to properly segregate during cell division. This can lead to various genetic disorders and abnormalities.

Formation

Acentric chromosomes are typically formed as a result of chromosomal aberrations, specifically chromosome breakage. This can occur spontaneously or be induced by external factors such as radiation or certain chemicals. When a chromosome breaks at two points and the fragment containing the centromere is lost, the remaining fragment is acentric.

Consequences

Without a centromere, acentric chromosomes are not included in the normal mitotic or meiotic segregation of chromosomes. They are not drawn to the cell poles during anaphase, and as a result, they do not end up in either of the daughter cells. This can lead to a loss of genetic material, which can have various effects depending on the genes located on the acentric chromosome.

In some cases, acentric chromosomes can be stabilized by the formation of a neocentromere, a functional but structurally different centromere. However, this is a rare event and does not occur in all organisms.

Clinical significance

Acentric chromosomes have been associated with various genetic disorders and conditions. For example, they are often found in cancer cells, where they can contribute to genomic instability and the progression of the disease. They can also lead to birth defects and infertility if they occur in germ cells.

See also

• Dicentric chromosome
• Ring chromosome
• Chromosome abnormality