Concept

Mutation

Overview

In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Mutations result from errors during replication, mitosis, meiosis, or damage to DNA, which then may trigger error-prone repair or cause an error during replication (translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements.

Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ultimate source of all genetic variation, providing the raw material on which evolutionary forces such as natural selection can act.

Mutation can result in many different types of change in sequences. Mutations in genes can have no effect, alter the product of a gene, or prevent the gene from functioning properly or completely. Mutations can also occur in non-genic regions. A 2007 study on genetic variations between different species of Drosophila suggested that, if a mutation changes a protein produced by a gene, the result is likely to be harmful, with an estimated 70% of amino acid polymorphisms having damaging effects, and the remainder being either neutral or marginally beneficial.

Mutation and DNA damage are the two major types of errors that occur in DNA, but they are fundamentally different. DNA damage is a physical alteration in the DNA structure, such as a single or double strand break, a modified guanosine residue in DNA such as 8-hydroxydeoxyguanosine, or a polycyclic aromatic hydrocarbon adduct. DNA damages can be recognized by enzymes, and therefore can be correctly repaired using the complementary undamaged strand in DNA as a template or an undamaged sequence in a homologous chromosome if it is available. If DNA damage remains in a cell, transcription of a gene may be prevented and thus translation into a protein may also be blocked. DNA replication may also be blocked and/or the cell may die. In contrast to a DNA damage, a mutation is an alteration of the base sequence of the DNA. Ordinarily, a mutation cannot be recognized by enzymes once the base change is present in both DNA strands, and thus a mutation is not ordinarily repaired. At the cellular level, mutations can alter protein function and regulation. Unlike DNA damages, mutations are replicated when the cell replicates. At the level of cell populations, cells with mutations will increase or decrease in frequency according to the effects of the mutations on the ability of the cell to survive and reproduce. Although distinctly different from each other, DNA damages and mutations are related because DNA damages often cause errors of DNA synthesis during replication or repair and these errors are a major source of mutation.

Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).

In the original texts

Passages from public-domain books where Mutation is discussed.

Be that as it may, the neo-Darwinians are inclined to admit that the periods of mutation are determinate. The direction of the mutation may therefore be so as well, at least in animals, and to the extent we shall have to indicate.
Henri Bergson, Creative Evolution
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If, however, a thing is called mutable by a power in itself, thus also in some manner every creature is mutable. For every creature has a twofold power, active and passive; and I call that power passive which enables anything to attain its perfection either in being, or in attaining to its end. Now if the mutability of a thing be considered according to its power for being, in that way all creatures are not mutable…
Aquinas Thomas, Summa Theologica, Part I
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Some of them appear to have no sensation; in others it is very dull. The body of some of them is naturally fleshy, as of those which are called tethya; and the acalephe and the sponge entirely resemble plants; the progress is always gradual by which one appears to have more life and motion than another. 4. In the vital actions also we may observe the same manner. For vegetables which are produced from seed appear to…
Aristotle, Aristotle's History of Animals In Ten Books
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But it is in the higher classes of animals that these changes of simple matter admit of the greatest variety. Let us contemplate for a moment some of the most remarkable mutations which any article of food (as, for example, flour-bread), which has been presented to the stomach, is destined to undergo in the animal frame. We know that the vital powers of the stomach will convert the starch, of which it principally…
Hippocrates, The genuine works of Hippocrates, Vol. 1
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Certainly the strenuous son of Menoetius is quite dead,-- for the word "quite" is pleonastic after the Attic fashion. Sometimes by several forms of speech he unfolds his meaning. This is called Periphrasis. As when he says "Sons of the Achaeans" for Achaeans, and the "Herculean might" for Hercules. Things are said figuratively by Mutation when the ordinary order is inverted. But he puts in an expression in the midst…
Plutarch, Complete Works of Plutarch — Volume 3
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Mutation

Overview

In the original texts

Philosophers who discussed Mutation

Related ideas

Opposing perspectives

Place in the tradition