Chromosomes are organized structures of DNA that are present in cells. The number of chromosomes in diploid cell varies in different organisms. The diploid chromosomes of a species contains two sets of chromosomes, and are indicated as 2n, where n = number of chromosomes. One set is contributed from the mother, and the other from the father. In haploid cells, like gametes, there is just one set of chromosomes indicated as 'n'.
In humans, most of the cells in the body are somatic cells or non-sex cells, which contain diploid number of chromosomes. The chromosomes contain pairs called homologous, and each and every somatic cell of the body has 46 chromosomes. There are 23 chromosomes from the mother's egg and 23 from father's sperm, thus making the diploid chromosome number as 46. This number makes up the genetic material of each individual human.
The diploid number is maintained by a process called mitosis, wherein a nuclear division process gives rise to identical sets of chromosomes. These sets are distributed to daughter cells during cell division. In meiosis, the diploid germ cells give rise to haploid cells, which contain half the number of chromosomes as that in the diploid ones. After fertilization of the egg and sperm, the number of chromosomes is restored after formation of zygote. However, even within the body, there are certain exceptions like liver cells, which may contain twice the number of diploid amount of DNA. Cancer cells in the body show aneuploidy, i.e., uneven number of chromosomes in the haploid number.
Diploid Chromosome Number in Different Organisms
|Drosophila (fruit fly)||8|
|Mouse-ear cress plant||10|
|South African clawed frog||36|
|Chinese muntjac (deer)||23|