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Genomics

life science Maturity 11-13 Next article →

Genomics is an interdisciplinary field of molecular biology. It focuses on the structure, function, evolution, mapping, and editing of genomes. A genome is the complete set of DNA in an organism. This includes all of its genes and its three-dimensional structural configuration. While genetics studies individual genes and inheritance, genomics looks at the whole collection. It characterizes and quantifies all genes together. It also studies how they relate to one another and influence the organism.

Metabolomics schema
Metabolomics schema

To understand life, we must understand how genes work. Genes can direct the production of proteins. This process uses enzymes and messenger molecules. Proteins are essential for building body structures like organs and tissues. They also control chemical reactions and carry signals between cells. Genomics explores these complex interactions. It studies phenomena like epistasis, where one gene affects another. It also looks at pleiotropy, where one gene affects multiple traits. Other studies include heterosis, also known as hybrid vigour.

Genome analysis follows a specific three-step process. First, scientists select a genome to study based on cost and relevance. Second, they perform sequencing to read the DNA. This is often done at centralized sequencing centers. These facilities use expensive instrumentation and technical support. Third, scientists perform annotation and analysis. This involves studying the sequence at the level of DNA, proteins, or gene pathways.

Genome sequencing project flowchart
Genome sequencing project flowchart

One way to read long DNA is shotgun sequencing. This method is used for sequences longer than 1,000 base pairs. It is named by analogy to a shotgun's firing pattern. Scientists break long DNA strands into small, random segments. They then sequence these short segments to obtain many "reads." Computer programs use the overlapping ends of these reads to assemble a continuous sequence. This process requires over-sampling to ensure every part is represented. This level of sampling is called coverage.

Environmental shotgun sequencing
Environmental shotgun sequencing

The history of genomics is full of major discoveries. In 1953, James D. Watson and Francis Crick published the structure of DNA. In 1955, Fred Sanger published the amino acid sequence of insulin. In 1964, Robert W. Holley determined the first nucleic acid sequence. This was the ribonucleotide sequence of alanine transfer RNA. In 1972, Walter Fiers determined the first gene sequence. He sequenced the coat protein gene for the bacteriophage MS2.

Sanger-sequencing
Sanger-sequencing

Frederick Sanger also helped develop crucial sequencing technologies. In 1975, he and Alan Coulson published the "Plus and Minus" technique. This used DNA polymerase and radiolabelled nucleotides. In 1977, his group sequenced the first fully DNA-based genome. This was the 5,386 nucleotide genome of the bacteriophage φX174. That same year, Walter Gilbert and Allan Maxam developed the Maxam-Gilbert method. This was a chemical method involving the cleavage of DNA at known bases. Gilbert and Sanger shared the 1980 Nobel Prize in Chemistry.

ABI PRISM 3100 Genetic Analyzer 3
ABI PRISM 3100 Genetic Analyzer 3

Sequencing projects have grown rapidly in scope and speed. In 1981, the human mitochondrion genome was reported. It was 16,568 base pairs long. In 1992, the first eukaryotic chromosome was sequenced. This was chromosome III of the yeast Saccharomyces cerevisiae. In 1995, the first free-living organism, Haemophilus influenzae, was sequenced. The Human Genome Project completed a rough draft in 2001. The full sequence was finished in 2003. By 2007, it was declared "finished" with very few errors.

Number of prokaryotic genomes and sequencing costs
Number of prokaryotic genomes and sequencing costs

Scientists use model organisms to study different types of life. Yeast is a model for eukaryotic cells. The fruit fly Drosophila melanogaster is a major tool for genetics. The worm Caenorhabditis elegans is used for multicellular studies. The zebrafish Brachydanio rerio helps with developmental studies. Plants like Arabidopsis thaliana serve as models for flowering plants. In mammals, mice and chimpanzees are important for medical research. Genomics is part of the "omics" revolution. This includes proteomics and metabolomics. These fields aim for the quantitative analysis of entire biological systems.

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🖼️ Images & Media (10)
File:Number of prokaryotic genomes and sequencing costs.svg
Number of prokaryotic genomes and...
File:Metabolomics schema.png
Metabolomics schema.png
File:Genome sequencing project flowchart.svg
Genome sequencing project flowchart.svg
File:Sanger-sequencing.svg
Sanger-sequencing.svg
File:ABI PRISM 3100 Genetic Analyzer 3.jpg
ABI PRISM 3100 Genetic Analyzer 3.jpg
File:Illumina Genome Analyzer II System.jpg
Illumina Genome Analyzer II System.jpg
File:Integrated microbial genomes.jpg
Integrated microbial genomes.jpg
File:Argonne's Midwest Center for Structural Genomics deposits 1,000th protein structure.jpg
Argonne's Midwest Center for Structural...
File:Environmental shotgun sequencing.png
Environmental shotgun sequencing.png
File:Human karyotype with bands and sub-bands.png
Human karyotype with bands and sub-bands.png
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