Human chromosomes karyotype. Computer artwork of a karyotype, an arrangement of the complete set of chromosomes of an animal, usually in order of size as they are seen under a light microscope. The chromosomes each consist of two identical chromatids joined at the centromere. There are 23 pairs of these chromosomes in the nucleus of nearly every cell in the body, 23 inherited from the mother and 23 from the father. They consist of genetic material, DNA (deoxyribonucleic acid), in association with proteins.