 Schematic of a region of a chromosome before and after a duplication event Gene duplication occurs when an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome leads to the duplication of a region of DNA containing a gene [1]. The significance of this process for evolutionary biology is that, unlike a single functional gene, which is usually subject to purifying selection and thus has a slowed mutation rate, one copy of a duplicate set of genes is often freed from selective pressure, allowing it to freely mutate. This is because with two copies of a gene present, mutations in just one copy of the gene often have no deleterious effect on the organism; thus, the second copy is free to "explore" the sequence space by mutating randomly. The duplicate gene may either (a) acquire mutations that lead to a gene with a novel function or (b) acquire deleterious mutations and become a pseudogene. Image File history File links Original source is from the Talking Glossary of Genetics http://www. ...
Chromosomal crossover is the process by which two chromosomes, paired up during Prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but to the different end piece. ...
Retrotransposons are genetic elements than can amplify themselves in a genome and are ubiquitous components of the DNA of many eukaryotic organisms. ...
This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ...
Evolutionary biology is a subfield of biology concerned with the origin and descent of species, as well as their change, multiplication, and diversity over time. ...
Stabilizing selection, also known as purifying selection or negative selection, is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. ...
Selection is hierachically classified into natural and artificial selection. ...
In biology, mutations are changes to the genetic material (either DNA or RNA). ...
A pseudogene is a nucleotide sequences that is similar to a normal gene, but is not expressed as a functional protein. ...
For over a 100 years, gene duplication is believed to play a major role in evolution[2], with Susumu Ohno being one of the most famous developers of this theory in his classical book “Evolution by gene duplication” (1970)[3]. Some have argued that gene duplication is the most important evolutionary force since the emergence of the universal common ancestor. Susumu Ohno (February 1, 1928 – January 13, 2000), was an Asian American geneticist and evolutionary biologist, and seminal researcher in the field of molecular evolution. ...
A group of organisms is said to have common descent if they have a common ancestor. ...
Major genome duplication events are not uncommon. It is retrodicted that the entire yeast genome underwent duplication about 100 million years ago. Plants are the most prolific genome duplicators. Wheat, for example, is hexaploid (a specific term for a polyploid organism) meaning it has six duplicate copies of its genome. Polyploidy refers to cells or organisms that contain more than two copies of each of their chromosomes. ...
In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ...
Polyploid (in Greek: πολλαπλόν - multiple) cells or organisms contain more than one copy (ploidy) of their chromosomes. ...
The two genes that exists after a gene duplication event are called paralogs. Paralogs usually code for proteins with a different function and/or structure, as stated above. This is different from orthologous genes, which code for proteins with similar functions but exist in different species. Orthologs are created from a speciation event. (See Homology of sequences in genetics). Used to describe two genes which share significant homology within the same species. ...
A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...
Used to describe two genes which share significant homology within the same species. ...
Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the theory of the evolutionary process by which new biological species are believed by some to arise. ...
In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. ...
It is important (but often hard) to differentiate between paralogs and orthologs in biological research. Experiments on human gene function can often be carried out on other species if a homolog to a human gene can be found in the genome of that species, but only if the homolog is orthologous. If they are paralogs and resulted from a gene duplication event, their functions are probably too different. In biology, a species is one of the basic units of biodiversity. ...
In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ...
References - ^ Zhang, J. (2003). "Evolution by gene duplication: an update." Trends in Ecology & Evolution 18(6): 292-298. DOI link
- ^ Taylor, JS. & Raes, J. (2004). "Duplication and Divergence: The Evolution of New Genes and Old Ideas" Annual Review of Genetics 9: 615-643. DOI link
- ^ Ohno, S. (1970). Evolution by gene duplication. Springer-Verlag. ISBN 0-04-575015-7.
Susumu Ohno (February 1, 1928 – January 13, 2000), was an Asian American geneticist and evolutionary biologist, and seminal researcher in the field of molecular evolution. ...
Springer Science+Business Media or Springer (IPA: ) is a worldwide publishing company based in Germany which focuses on academic journals and books in the fields of science, technology and medicine. ...
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