Cell Physiology : Females Are 46,XX; Males Are 46,XY
Diploid: Having a pair of each type of chromosome, so that the basic chromosome number is doubled, e.g., diploid somatic cells.
Sequencing the human genome has allowed geneticists to make global estimates of the level of DNA sequence variability found in the human population. Each diploid human cell contains approximately 6 billion base pairs of DNA. Prevailing estimates of the sequence variation between any two humans is on the order of 0.1 percent,1,2 or approximately 6 million differences. This 0.1 percent sequence variation is thought to be responsible for all of the genetic variation observed in the human population, including the sizable genetic components of a large number of human diseases, both common and rare, as well as all of the quantitative genetic traits, such as height and skin color, that make for obvious phenotypic differences between individuals.
Resource: The Ensembl Project, Human Genome Browser
The estimate of 0.1 percent sequence difference between any two humans applies, in the strictest sense, only to comparisons made between two females or two males. The X and Y chromosomes have been genetically isolated for hundreds of millions of years so that even those portions that are homologous are very substantially diverged in sequence.3 The human Y chromosome contains only 60 million base pairs of DNA on average. In contrast, the human X chromosome contains 160 million base pairs.4
