: Each species has a fixed number of chromosomes in its cells. For example, human beings have 46 chromosomes in every body cell. The 46 chromosomes in an ordinary human cell are of 23 different kinds. Of these, 22 pairs are autosomes and one pair is of sex chromosomes. The gametes or the sex cells contain only half the number of chromosomes (haploid). A cell which has the full number of chromosomes is called a diploid cell.