Genomics is the study of the genomes of organisms. The field includes intensive efforts to determine the entire DNA sequence of organisms and fine-scale genetic mapping efforts.
The field also includes studies of intragenomic phenomena such as heterosis, epistasis, pleiotropy and other interactions between loci and alleles within the genome. In contrast, the investigation of the roles and functions of single genes is a primary focus of molecular biology or genetics and is a common topic of modern medical and biological research. Research of single genes does not fall into the definition of genomics unless the aim of this genetic, pathway, and functional information analysis is to elucidate its effect on, place in, and response to the entire genome's networks.
For the United States Environmental Protection Agency, "the term "genomics" encompasses a broader scope of scientific inquiry associated technologies than when genomics was initially considered. A genome is the sum total of all an individual organism's genes. Thus, genomics is the study of all the genes of a cell, or tissue, at the DNA (genotype), mRNA (transcriptome), or protein (proteome) levels."
Genomics was established by Fred Sanger when he first sequenced the complete genomes of a virus and a mitochondrion. His group established techniques of sequencing, genome mapping, data storage, and bioinformatic analyses in the 1970-1980s.
A major branch of genomics is still concerned with sequencing the genomes of various organisms, but the knowledge of full genomes has created the possibility for the field of functional genomics, mainly concerned with patterns of gene expression during various conditions.
The most important tools here are microarrays and bioinformatics. Study of the full set of proteins in a cell type or tissue, and the changes during various conditions, is called proteomics.
A related concept is materiomics, which is defined as the study of the material properties of biological materials (e.g. hierarchical protein structures and materials, mineralized biological tissues, etc.) and their effect on the macroscopic function and failure in their biological context, linking processes, structure and properties at multiple scales through a materials science approach.
The actual term 'genomics' is thought to have been coined by Dr. Tom Roderick, a geneticist at the Jackson Laboratory (Bar Harbor, ME) at a meeting held in Maryland on the mapping of the human genome in 1986.
In 1972, Walter Fiers and his team at the Laboratory of Molecular Biology of the University of Ghent (Ghent, Belgium) were the first to determine the sequence of a gene: the gene for Bacteriophage MS2 coat protein. In 1976, the team determined the complete nucleotide-sequence of bacteriophage MS2-RNA. The first DNA-based genome to be sequenced in its entirety was that of bacteriophage Φ-X174; (5,368 bp), sequenced by Frederick Sanger in 1977.
The first free-living organism to be sequenced was that of ''Haemophilus influenzae'' in 1995, and since then genomes are being sequenced at a rapid pace.
As of September 2007, the complete sequence was known of about 1879 viruses , 577 bacterial species and roughly 23 eukaryote organisms, of which about half are fungi.
Most of the bacteria whose genomes have been completely sequenced are problematic disease-causing agents, such as ''Haemophilus influenzae''. Of the other sequenced species, most were chosen because they were well-studied model organisms or promised to become good models. Yeast (''Saccharomyces cerevisiae'') has long been an important model organism for the eukaryotic cell, while the fruit fly ''Drosophila melanogaster'' has been a very important tool (notably in early pre-molecular genetics). The worm ''Caenorhabditis elegans'' is an often used simple model for multicellular organisms. The zebrafish ''Brachydanio rerio'' is used for many developmental studies on the molecular level and the flower ''Arabidopsis thaliana'' is a model organism for flowering plants. The Japanese pufferfish (''Takifugu rubripes'') and the spotted green pufferfish (''Tetraodon nigroviridis'') are interesting because of their small and compact genomes, containing very little non-coding DNA compared to most species.
A rough draft of the human genome was completed by the Human Genome Project in early 2001, creating much fanfare. By 2007 the human sequence was declared "finished" (less than one error in 10,000 bases and all chromosomes assembled. Display of the results of the project required significant bioinformatics resources. The sequence of the human reference assembly can be explored using the UCSC Genome Browser.
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