In humans, each cell normally contains 23 pairs of chromosomes, The 23rd pair, the sex chromosomes, differ between males and females. Comparisons between X-linked and autosomal variation in humans give a mixed picture. Hammer et al. resequenced > kb of noncoding human DNA, finding. A chromosome is a long DNA molecule with part or all of the genetic material of an organism. Diagram of a replicated and condensed metaphase eukaryotic chromosome. Chromosomal recombination during meiosis and subsequent sexual The number of human chromosomes was published in by Theophilus. Sex Chromosomes. The remaining pair of human chromosomes consists of the sex chromosomes, X and Y. Females have two.