. In other words, a chromatid is "one-half of a replicated chromosome". Chromatid - A Cell Biology Definition It shouldn't be confused with the ploidy of an organism, which is the number of homologous versions of a chromosome. Quantity In humans, for example, there are normally 23 pairs of homologous chromosomes in each cell (N=23). However, the quantity of chromatids will be a multiple of 23. It can be either 4N, 2N or 1N. N doesn't refer to haploid or diploid; it refers to the number of chrom… (More on Chromatids)