Ploidy refers to the number of sets of homologous chromosomes in the genome of a cell or an organism. Each set is designated by n. Thus, the term diploidy would refer to a state of being diploid, that is having two sets of the chromosomes (and therefore two copies of genes), especially in somatic cells. A diploid is a cell or an organism having two sets of homologous chromosomes and is represented by 2n. For instance, a human somatic cell is in diploid state since it contains 46 chromosomes (in contrast to the sex cell that contains only 23 chromosomes). The 46 chromosomes in somatic cell results from the presence of two sets of chromosomes – one set derived from the father and another set from the mother. The haploid gametes from the parents would unite during fertilization resulting in the development into a zygote, which is now diploid.
Word origin: from Greek diplous, double
- diploid (adjective and noun)