Genomics is the study of an organism's genome and the use of the genes. It deals with the systematic use of genome information, associated with other data, to provide answers in biology, medicine, and industry.
Genomics has the potential of offering new therapeutic methods for the treatment of some diseases, as well as new diagnostic methods. Other applications are in the food and agriculture sectors. The major tools and methods related to genomics are bioinformatics, genetic analysis, measurement of gene expression, and determination of gene function.
The first genome to be sequenced in its entirety was that of bacteriophage FX174 (5,368 kb) in 1980. The first free-living organism to be sequenced was that of Haemophilus influenzae (1.8Mb) in 1995, and since then genomes are being sequenced at a rapid pace. A rough draft of the human genome was completed by the Human Genome Project in early 2001 amid much fanfare.
Main article: -omics
The original use of the suffix "ome" (from the Greek for 'all', 'every' or 'complete') was "genome", which refers to the complete genetic makeup of an organism. Because of the success of large-scale quantitative biology projects such as genome sequencing, the suffix "ome" has been extended to a host of other contexts. The only other "ome" to shake its origin as a buzzword is proteome, the totality of proteins (expressed genes that are translated) in an organism, tissue type or cell, and proteomics is now well-established as a term for studying the proteome.
Main article: Comparative genomics
Comparison of genomes has resulted in some surprising biological discoveries. If a particular DNA sequence or pattern is present among many members of a clade, that sequence is said to have been conserved among the species. Evolutionary conservation of a DNA sequence may imply that it confers a relative selective advantage to the organisms that possess it. Conservation also suggests that sequence has functional significance. It may be a protein coding sequence or regulatory region. Experimental investigation of some of these sequences has shown that some are transcribed into small RNA molecules, although the functions of these RNAs were not immediately apparent.
The identification of similar sequences (including many genes) in two distantly related organisms, but not in other members of one of the clades, has led to the theory that these sequences were acquired by horizontal gene transfer. This phenomenon is most prominent in thermophilic bacteria, where it seems that genes were transferred from Archaea to Eubacteria. It has also been noticed that bacterial genes exist in eukaryotic nuclear genomes and that these genes generally encode mitochondrial and plastid proteins, giving support to the endosymbiotic theory of the origin of these organelles.
It is often stated that a particular organism shares X percent of its DNA with humans. This number indicates the percentage of base pairs that are identical between the two species. Here is a list of genetic similarity to humans, with sources, where known.
While these numbers come from various secondary sources, the data may have originated from measures of DNA-DNA hybridization or from direct sequence comparisons.
|Human||99.9%||quoted by President Clinton, Jan 2000, State of the Union address; also Human Genome Project|
|Chimpanzee||98.4%||sources: Americans for Medical Progress ; Jon Entine in the San Francisco Examiner|
|98.7%||Richard Mural of Celera Genomics, quoted on MSNBC|
|Bonobo||equal to chimpanzee|
|Gorilla||98.38%||based on study of intergenic nonrepetitive DNA in Am J Hum Genet. (2001) Feb;682:444-56|
|Mouse||98%||source: Americans for Medical Progress|
|85%||comparing all protein coding sequences, NHGRI|
|Dog||95%||Jon Entine in the San Francisco Examiner|
|C. elegans||74%||Jon Entine in the San Francisco Examiner|
|Banana||50%||source: Americans for Medical Progress|
|Daffodil||35%||Steven Rose in The Guardian 22 Jan 2004|