Acrocentric

Acrocentric

An acrocentric chromosome is a type of chromosome in which the centromere is located quite near one end of the chromosome, resulting in one very long arm and one very short arm. This configuration is distinct from other types of chromosomes, such as metacentric and submetacentric chromosomes, where the centromere is located more centrally.

Structure

In acrocentric chromosomes, the centromere is positioned such that the p (short) arm is significantly shorter than the q (long) arm. This asymmetrical structure can be important in the context of genetic recombination and chromosomal translocations. The short arm of acrocentric chromosomes often contains repetitive sequences and ribosomal RNA genes.

Human Acrocentric Chromosomes

In humans, there are five pairs of acrocentric chromosomes: chromosomes 13, 14, 15, 21, and 22. These chromosomes are notable for their role in forming Robertsonian translocations, a common type of chromosomal rearrangement that can lead to genetic disorders such as Down syndrome.

Function

The short arms of acrocentric chromosomes are known to carry multiple copies of genes encoding ribosomal RNA (rRNA), which are essential for the formation of ribosomes and protein synthesis. These regions are often involved in the formation of the nucleolus, a substructure within the nucleus where ribosome assembly begins.

Clinical Significance

Acrocentric chromosomes are involved in several genetic conditions due to their propensity to undergo Robertsonian translocations. Such translocations can lead to an imbalance in genetic material, resulting in conditions like Down syndrome, Patau syndrome, and other chromosomal disorders. Genetic counseling and karyotyping are often used to detect these translocations in affected individuals or carriers.

Also see

• Chromosome
• Centromere
• Robertsonian translocation
• Down syndrome
• Karyotype