The human genome contains approximately:
A. 35,000 to 40,000 genesGenome is a collective term for all genes present in one organism. The human genome contains DNA sequences of 3 billion base pairs, carried by 23 pairs of chromosomes. The human genome has an estimated 25,000 to 30,000 genes, and overall, it is 99.9% identical in all people. Approximately 3 million locations where single-base DNA differences exist have been identified and termed single nucleotide polymorphisms. Single nucleotide polymorphisms may be critical determinants of human variation in disease susceptibility and responses to environmental factors.