Entry
Entries A-Z
Human Genome
The whole set of hereditary information encoded in DNA, including the genes and the noncoding sequences of DNA. The human genome has 46 chromosomes (22 distinct autosomal pairs and the sex chromosomes), which hold approximately 3 billion DNA base pairs and contain an estimated 20,000 to 25,000 genes. The human genome has fewer genes than expected—less than two times that of many lower-order species, such as the fruit fly. However, some human genes are capable of coding for more than one protein, through a process known as alternative splicing. For more information, see The Human Genome Project Web site.