Kromosoomiparien

Kromosoomiparien are pairs of homologous chromosomes found in the nuclei of diploid cells. Each pair consists of one chromosome inherited from the mother and one from the father. The two chromosomes in a pair carry the same genes in the same order, though the specific versions (alleles) of those genes may differ between the two chromosomes.

In humans, somatic cells contain 23 chromosome pairs, for a total of 46 chromosomes. Of these, 22 pairs are autosomes and 1 pair consists of the sex chromosomes (XX in females, XY in males). Gametes (sperm and egg cells) are haploid and carry one chromosome from each pair, totaling 23 chromosomes.

Homologous chromosome pairs share a high degree of similarity in length, centromere position, and gene content, but they are not identical. During meiosis, recombination or crossing over can occur between homologous chromosomes, creating new combinations of alleles. This genetic exchange, along with the independent assortment of chromosome pairs, contributes to genetic variation. During mitosis, replicated chromosomes condense into sister chromatids, which separate to produce two genetically identical daughter cells; the concept of chromosome pairs is most evident in the diploid phase of the life cycle.

Chromosome pairing and number vary across species. Karyotyping reveals the number and structure of chromosome pairs, and deviations from the normal diploid number can indicate genetic abnormalities. Polyploid species have more than two complete sets of chromosomes, and aneuploidy refers to the gain or loss of individual chromosomes, often with clinical consequences.