| 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.
History
Genomics appeared in the 1980s and took off in the 1990s with the initiation of genome projects for several species. The related field of genetics is the study of genes and their role in inheritance.
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.
The growth of the "omics"
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.
Comparative genomics
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.
Genetic similarity
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.
| Species |
Similarity |
Source |
| Human |
99.9% |
quoted by President Clinton, Jan 2000, State of the Union address; also Human Genome Project |
| 100% |
identical twins |
| 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 |
Sources and external links
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