diploide

Diploide, or diploidy, is a condition in which a cell or organism carries two complete sets of chromosomes (2n). This is the standard chromosome configuration in most somatic cells of animals and many plants, in contrast to haploidy (n), where only a single chromosome set is present. In species with sexual reproduction, gametes are typically haploid and arise by meiosis, ensuring that fertilization restores diploidy in the zygote.

The diploid state provides genetic redundancy, allowing one chromosome to withstand deleterious mutations with the help of its homologous partner. It also enables genetic recombination during meiosis, creating new allele combinations and increasing genetic diversity, a key factor in adaptation.

Examples include humans, where the diploid chromosome number is 46 (23 pairs). Other organisms vary, and some are polyploid, having more than two chromosome sets (for example triploidy 3n or tetraploidy 4n). Polyploidy is common in plants and can arise through genome doubling or hybridization (autopolyploidy, allopolyploidy).

Life cycle notes: In animals, the diploid phase typically dominates; fertilization produces a diploid zygote that develops into a multicellular diploid organism. In many plants and algae, there is an alternation of generations with both diploid sporophyte and haploid gametophyte phases.

Detection and relevance: Ploidy level can be determined by karyotyping or flow cytometry. Abnormal ploidy, such as aneuploidy (extra or missing chromosomes), can cause developmental disorders and diseases.