Diploid

Definition

Having two complete sets of chromosomes per cell (2n), typically one maternal and one paternal, forming homologous pairs. In arthropods, diploidy is the standard somatic condition for sexually reproducing species, though haplodiploid systems (males haploid, females diploid) occur in Hymenoptera and some mites, and polyploidy arises in certain parthenogenetic lineages.

Etymology

From Greek diplous (double) + -oid (resembling), referring to the doubled chromosome complement.

Example

A female honey bee worker is diploid (2n = 32), carrying two sets of chromosomes and being capable of laying haploid eggs that develop into males via arrhenotoky, whereas males are haploid (n = 16).

Synonyms

• 2n

Related Terms

• haploid
• polyploid
• Haplodiploidy
• Chromosome
• zygote
• Meiosis
• Parthenogenesis
• karyotype

Usage Notes

Diploid contrasts with haploid (gametes, n) and polyploid (three or more sets). In cytogenetic shorthand, '2n' denotes the diploid chromosome number. Some specialists reserve 'diploid' strictly for organisms with two sets from distinct parents, using 'amphidiploid' or 'allodiploid' for hybrid-derived diploids. In entomological genetics, distinguishing diploid from haplodiploid systems is essential for predicting sex ratios and breeding experiments.