MoBio Chromosome Numbers Chapter 1

A germ cell (sperm or egg) contains only one set of chromosomes. It belongs to haploid, represented as 1n. Somatic cells (cells other than germ cells) of sexually reproducing organisms are diploid, denoted by 2n. In humans, the haploid chromosome number is 23, but the diploid chromosome number is 46.


Table 1-C-1. Chromosome numbers of common species.


Smallest number: The female of a subspecies of the ant, Myrmecia pilosula, has one pair of chromosomes per cell. Its male has only one chromosome in each cell.

Largest number: In the fern family of plants, the species Ophioglossum reticulatum has about 630 pairs of chromosomes, or 1260 chromosomes per cell.