Ykromosoomi

Ykromosoomi, commonly known as the Y chromosome, is one of the two sex chromosomes in species with XY sex-determination systems. In humans and many other mammals, individuals with a Ykromosoomi paired with an Xkromosoomi develop as males, while those with two Xkromosoomi develop as females. The Ykromosoomi is passed from father to son, making it useful for tracing patrilineal ancestry.

Structure and genes

The Ykromosoomi is relatively small, containing roughly 59 million base pairs in humans. Much of it does not recombine with the X chromosome during meiosis, a region known as the non-recombining region of the Y (NRY). At the ends of the chromosome are two small regions of homology with the X chromosome, called pseudoautosomal regions (PAR1 and PAR2), where recombination can occur. The Ykromosoomi carries a limited set of protein-coding genes, many of which are involved in male sex development and spermatogenesis. Notable genes include SRY, which triggers male development during embryogenesis, and gene families such as DAZ, RBMY, and CDY that play roles in sperm production. The chromosome also contains numerous repetitive sequences and palindromic regions that facilitate gene conversion and maintain gene integrity.

Evolution and significance

Compared with the X chromosome, the Ykromosoomi has undergone substantial gene loss over evolutionary time, though it has retained genes essential for male development and fertility. Its history is frequently studied to understand human ancestry and paternal lineages; Y-kromosome haplotypes are used in population genetics and forensic genetics through Y-STR markers.

Clinical relevance

Deletions or rearrangements in the Ykromosoomi, especially in the AZF (azoospermia factor) regions on Yq, can cause infertility. Testing of Ykromosoomi variants informs diagnoses in male infertility and is used in paternity and forensic analyses.