acrocêntricos

Acrocentric chromosomes are a type of chromosome that has its centromere located very close to one end, giving it a characteristic V or J shape during cell division. The centromere is the constricted region of a chromosome that separates it into a short arm (p arm) and a long arm (q arm). In acrocentric chromosomes, the p arm is extremely short and may contain only a few genes. The q arm, in contrast, is much longer.

Humans have five pairs of acrocentric chromosomes: chromosomes 13, 14, 15, 21, and 22. These chromosomes also contain genes for ribosomal RNA (rRNA) and have a specific structure called a stalk that is involved in nucleolus formation. Due to the very short p arms, the genetic material on these arms is often considered dispensable.

The presence of acrocentric chromosomes is important in genetics. For example, translocations involving acrocentric chromosomes, where parts of chromosomes break off and reattach to other chromosomes, can lead to genetic disorders. Down syndrome, for instance, is caused by trisomy of chromosome 21, which is an acrocentric chromosome. The unique structure of acrocentric chromosomes also plays a role in chromosome segregation during meiosis.