acrocentrikus

Acrocentric chromosomes are a specific type of chromosome characterized by their structural arrangement, where the centromere (the region where sister chromatids are joined) is located very close to one end. This positioning results in a short arm (p arm) and a long arm (q arm), with the p arm being significantly smaller than the q arm. The term "acrocentric" derives from the Greek words *akros* (meaning "extreme" or "point") and *kentron* (meaning "center"), reflecting the centromere’s position near the chromosome’s terminus.

In humans, five pairs of chromosomes are classified as acrocentric: chromosomes 13, 14, 15, 21, and 22. These chromosomes also contain nucleolar organizer regions (NORs) on their short arms, which are critical for ribosomal RNA synthesis and the formation of nucleoli within the cell nucleus. The acrocentric structure of these chromosomes plays a role in genetic disorders, particularly those involving numerical abnormalities such as trisomy 21 (Down syndrome), which results from the presence of an extra copy of chromosome 21.

Acrocentric chromosomes exhibit unique behaviors during cell division, including the tendency to form satellite structures on their short arms. These satellites are often rich in repetitive DNA sequences and can detach from the main chromosome body. Additionally, acrocentric chromosomes are notable for their involvement in chromosomal rearrangements, such as translocations, which can occur between different acrocentric chromosomes or between an acrocentric and a non-acrocentric chromosome.

The study of acrocentric chromosomes is important in genetics, cytogenetics, and medical diagnostics, as their structural features influence inheritance patterns and contribute to the understanding of genetic disorders. Advances in molecular biology have further clarified their role in gene expression and cellular function.