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Longman Dictionary of Contemporary English
▪ Now, suppose that deleterious mutations reduce survival below this optimal value.
▪ Senescence of clones is probably caused by the accumulation of deleterious mutations.
▪ Furthermore, the total rate of production of deleterious mutations and their pattern of age-specificity are unknown.
▪ Suppose now that deleterious mutations are age-specific.
▪ Andean vultures become avid for the life-giving molecule with quite a different set of mutations.
▪ Over 40 different mutations of the phenylalanine hydroxylase gene have been identified.
▪ Ironically, a similar belief prevails today, in a slightly different mutation.
▪ This is a worthwhile approach, though one should bear in mind that different mutagens give qualitatively different kinds of mutation.
▪ Fears that radiotherapy would cause genetic mutations leading to handicaps in offspring appear to be groundless, according to studies among 3,000 survivors.
▪ But in the 1980s, scientists found that a genetic mutation was responsible.
▪ Variations occur within a population, explicable as genetic mutations or the results of mixing of genetic material.
▪ On the other hand, most cases of the disease seem to develop without genetic mutations, Gibbs said.
▪ With enough genetic mutations at hand, the behaviour could perhaps have evolved independently in each species.
▪ Some people may have a predisposition to the genetic mutations that lead to disease.
▪ Evolution requires genetic change, mutation.
▪ Trichloroethene, a probable human carcinogen, can cause liver damage and genetic mutations in both human and animal populations.
▪ Long-inbred populations might be useful for assessing the effects of new mutations.
▪ It is people like Dawkins who are the new genetic mutations which will spread only if they have superior survival value.
▪ In outbred populations, selection acts on new mutations mainly through their heterozygous effects.
▪ It presses new mutations into service as they arise and is just as ready to make do with what is already around.
▪ When necessary, bacteria cheat to ensure a supply of new mutations.
▪ To begin with, this was the only such pattern in existence, but then a new mutation arose.
▪ Whether his fainting goats were a new mutation or part of an older breed remains unclear.
▪ In splurge-weed, the new mutation can arise in any cell, in any branch of the plant.
▪ When they seemed to resemble each other rather too closely, he introduced random mutations in the offspring.
▪ The genes that cause the elaborate ornament or long tail to appear are subject to random mutation.
▪ Our random mutation is essential because it is unnecessary.
▪ The more elaborate the ornament, the more likely that a random mutation will make the ornament less elaborate, not more.
▪ We want them to emerge solely as a result of cumulative selection of random mutations.
▪ It follows that some process other than random mutation and selection must be involved.
▪ K-ras gene mutations, by contrast with p53, clearly occur at an earlier stage in the neoplastic sequence.
▪ Other workers have found ras gene mutations in between 39% and 47% of colorectal cancers.
▪ Enough premalignant cells are present in the bulk of stool to permit the analysis of tumour suppressor gene mutations by this technique.
▪ Loss of tumour suppressor function requires inactivation of both alleles, usually by chromosomal deletion or point mutation, or both.
▪ The use of immunohistochemical staining as a marker of point mutation has been critically reviewed by Wyndord-Thomas.
▪ Nineth five percent of large bowel cancers showing loss of heterozygosity for 17p alleles also contain a point mutation.
▪ Thus, both of the point mutations characterized here would be expected to eliminate kinase activity of the proposed atk protein product.
▪ Apart from point mutation, another way in which oncogenes can be activated is by over expression.
▪ If mutagens like cosmic rays are present then all normal mutation rates are boosted.
▪ It strives for a mutation rate of zero.
▪ For the last 20 years researchers have been able to calculate genome sizes and mutation rates.
▪ By far the shakiest part of the calculation is the average mutation rate.
▪ Moreover, mutation rates seem to change with the physiological state of the organism.
▪ Yes, this is the inverse of what is known as the mutation rate, and it can be measured.
▪ That is, the rate of substitution equals the neutral mutation rate.
▪ They are free to evolve at the mutation rate.
▪ Fears that radiotherapy would cause genetic mutations leading to handicaps in offspring appear to be groundless, according to studies among 3,000 survivors.
▪ Tests have shown them to restrict growth and cause mutations in micro-organisms.
▪ Each digestion included a positive colorectal carcinoma or adenoma control known to contain a mutation at codon 12.
▪ Nineth five percent of large bowel cancers showing loss of heterozygosity for 17p alleles also contain a point mutation.
▪ Other workers have found ras gene mutations in between 39% and 47% of colorectal cancers.
▪ But in the 1980s, scientists found that a genetic mutation was responsible.
▪ If this shows a lethal mutation it is classified as a presumed mammalian mutagen.
▪ A minor mutation should be deemed an eccentricity and nothing more.
▪ A second bug experienced a mutation that allowed it to make use of the acetate excreted from the first.
▪ By far the shakiest part of the calculation is the average mutation rate.
▪ For the last 20 years researchers have been able to calculate genome sizes and mutation rates.
▪ If mutagens like cosmic rays are present then all normal mutation rates are boosted.
▪ Living organisms have a similar tradeoff in deciding how much mutation and innovation is needed to keep up with a changing environment.
▪ Previously, disease-causing mutations have been linked to rare or incurable disorders, providing often debatable benefits to small numbers of people.
▪ The other mode depends on occasional small mutations, like the changes in the parameters of protozoa.
The Collaborative International Dictionary

mutation \mu*ta"tion\ (m[-u]*t[=a]"sh[u^]n), n. [L. mutatio, fr. mutare to change: cf. F. mutation. See Mutable.] Change; alteration, either in form or qualities. The vicissitude or mutations in the superior globe are no fit matter for this present argument. --Bacon. 2. (Biol.) Gradual definitely tending variation, such as may be observed in a group of organisms in the fossils of successive geological levels. 3. (Biol.)

  1. As now employed (first by de Vries), a cellular process resulting in a sudden inheritable variation (the offspring differing from its parents in some well-marked character or characters) as distinguished from a gradual variation in which the new characters become fully developed only in the course of many generations. The occurrence of mutations, the selection of strains carrying mutations permitting enhanced survival under prevailing conditions, and the mechanism of hereditary of the characters so appearing, are well-established facts; whether and to what extent the mutation process has played the most important part in the evolution of the existing species and other groups of organisms is an unresolved question.

  2. The result of the above process; a suddenly produced variation.

    Note: Mutations can occur by a change in the fundamental coding sequence of the hereditary material, which in most organisms is DNA, but in some viruses is RNA. It can also occur by rearrangement of an organism's chromosomes. Specific mutations due to a change in DNA sequence have been recognized as causing certain specific hereditary diseases. Certain processes which produce variation in the genotype of an organism, such as sexual mixing of chromosomes in offspring, or artificially induced recombination or introduction of novel genetic material into an organism, are not referred to as mutation.

    4. (Biol.) a variant strain of an organism in which the hereditary variant property is caused by a mutation[3].

Douglas Harper's Etymology Dictionary

late 14c., "action of changing," from Old French mutacion (13c.), and directly from Latin mutationem (nominative mutatio) "a changing, alteration, a turn for the worse," noun of action from past participle stem of mutare "to change" (see mutable). Genetic sense is from 1894.


n. 1 Any alteration or change. 2 (context genetics English) Any heritable change of the base-pair sequence of genetic material.

  1. n. (biology) an organism that has characteristics resulting from chromosomal alteration [syn: mutant, variation, sport]

  2. (genetics) any event that changes genetic structure; any alteration in the inherited nucleic acid sequence of the genotype of an organism [syn: genetic mutation, chromosomal mutation]

  3. a change or alteration in form or qualities


In biology, a mutation is the permanent alteration of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA or other genetic elements. Mutations result from damage to DNA which then may undergo error-prone repair (especially microhomology-mediated end joining), or cause an error during other forms of repair, or else may cause an error during replication ( translesion synthesis). Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce discernible 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 can result in many different types of change in sequences. Mutations in genes can either have no effect, alter the product of a gene, or prevent the gene from functioning properly or completely. Mutations can also occur in nongenic regions. One study on genetic variations between different species of Drosophila suggests that, if a mutation changes a protein produced by a gene, the result is likely to be harmful, with an estimated 70 percent of amino acid polymorphisms that have damaging effects, and the remainder being either neutral or marginally beneficial. Due to the damaging effects that mutations can have on genes, organisms have mechanisms such as DNA repair to prevent or correct mutations by reverting the mutated sequence back to its original state.

Mutation (disambiguation)

A mutation is a change in the sequence of an organism's genetic material.

Mutation may also refer to:

Mutation (novel)

Mutation is a book written by Robin Cook about the ethics of genetic engineering. It brings up the benefits, risks, and consequences.

Mutation (algebra)

In the theory of algebras over a field, mutation is a construction of a new binary operation related to the multiplication of the algebra. In specific cases the resulting algebra may be referred to as a homotope or an isotope of the original.

Mutation (genetic algorithm)

Mutation is a genetic operator used to maintain genetic diversity from one generation of a population of genetic algorithm chromosomes to the next. It is analogous to biological mutation. Mutation alters one or more gene values in a chromosome from its initial state. In mutation, the solution may change entirely from the previous solution. Hence GA can come to better solution by using mutation. Mutation occurs during evolution according to a user-definable mutation probability. This probability should be set low. If it is set too high, the search will turn into a primitive random search.

The classic example of a mutation operator involves a probability that an arbitrary bit in a genetic sequence will be changed from its original state. A common method of implementing the mutation operator involves generating a random variable for each bit in a sequence. This random variable tells whether or not a particular bit will be modified. This mutation procedure, based on the biological point mutation, is called single point mutation. Other types are inversion and floating point mutation. When the gene encoding is restrictive as in permutation problems, mutations are swaps, inversions, and scrambles.

The purpose of mutation in GAs is preserving and introducing diversity. Mutation should allow the algorithm to avoid local minima by preventing the population of chromosomes from becoming too similar to each other, thus slowing or even stopping evolution. This reasoning also explains the fact that most GA systems avoid only taking the fittest of the population in generating the next but rather a random (or semi-random) selection with a weighting toward those that are fitter.

For different genome types, different mutation types are suitable:

  • Bit string mutation
The mutation of bit strings ensue through bit flips at random positions. Example:

|1 || 0 || 1 || 0 || 0 || 1 || 0 |- | || || || || ↓ || || |- |1 || 0 || 1 || 0 || 1 || 1 || 0 |}

The probability of a mutation of a bit is $\frac{1}{l}$, where l is the length of the binary vector. Thus, a mutation rate of 1 per mutation and individual selected for mutation is reached.
  • Flip Bit

This mutation operator takes the chosen genome and inverts the bits (i.e. if the genome bit is 1, it is changed to 0 and vice versa).

  • Boundary

This mutation operator replaces the genome with either lower or upper bound randomly. This can be used for integer and float genes.

  • Non-Uniform

The probability that amount of mutation will go to 0 with the next generation is increased by using non-uniform mutation operator. It keeps the population from stagnating in the early stages of the evolution. It tunes solution in later stages of evolution. This mutation operator can only be used for integer and float genes.

  • Uniform

This operator replaces the value of the chosen gene with a uniform random value selected between the user-specified upper and lower bounds for that gene. This mutation operator can only be used for integer and float genes.

  • Gaussian

This operator adds a unit Gaussian distributed random value to the chosen gene. If it falls outside of the user-specified lower or upper bounds for that gene, the new gene value is clipped. This mutation operator can only be used for integer and float genes.

Mutation (knot theory)

In the mathematical field of knot theory, a mutation is an operation on a knot that can produce different knots. Suppose K is a knot given in the form of a knot diagram. Consider a disc D in the projection plane of the diagram whose boundary circle intersects K exactly four times. We may suppose that (after planar isotopy) the disc is geometrically round and the four points of intersection on its boundary with K are equally spaced. The part of the knot inside the disc is a tangle. There are two reflections that switch pairs of endpoints of the tangle. There is also a rotation that results from composition of the reflections. A mutation replaces the original tangle by a tangle given by any of these operations. The result will always be a knot and is called a mutant of K.

Mutants can be difficult to distinguish as they have a number of the same invariants. They have the same hyperbolic volume (by a result of Ruberman), and have the same HOMFLY polynomials.

Mutation (Jordan algebra)

In mathematics, a mutation, also called a homotope, of a unital Jordan algebra is a new Jordan algebra defined by a given element of the Jordan algebra. The mutation has a unit if and only if the given element is invertible, in which case the mutation is called a proper mutation or an isotope. Mutations were first introduced by Max Koecher in his Jordan algebraic approach to Hermitian symmetric spaces and bounded symmetric domains of tube type. Their functorial properties allow an explicit construction of the corresponding Hermitian symmetric space of compact type as a compactification of a finite-dimensional complex semisimple Jordan algebra. The automorphism group of the compactification becomes a complex subgroup, the complexification of its maximal compact subgroup. Both groups act transitively on the compactification. The theory has been extended to cover all Hermitian symmetric spaces using the theory of Jordan pairs or Jordan triple systems. Koecher obtained the results in the more general case directly from the Jordan algebra case using the fact that only Jordan pairs associated with period two automorphisms of Jordan algebras are required.

Usage examples of "mutation".

He went to the bathroom to wash his hands, but this time he did not ask the mirror, metaphysically, What can this be, he had recovered his scientific outlook, the fact that agnosia and amaurosis are identified and defined with great precision in books and in practice, did not preclude the appearance of variations, mutations, if the word is appropriate, and that day seemed to have arrived.

So perhaps he had an edited cerebral chemistry, or an adaptive aural processing mutation in his derivative Kido lineage.

On Gris we send biogenetic teams to Earth every five years to check our own mutation rate.

From the undoubted fact that gene mutations like the Tay-Sachs mutation or chromosomal abnormalities like the extra chromosome causing Down syndrome are the sources of pathological variation, human geneticists have assumed that heart disease, diabetes, breast cancer, and bipolar syndrome must also be genetic variants.

He has to admit, however, that atoms do not aggregate of their own accord, and rather than believe in a superior law and, finally, in the destiny he wishes to deny, he accepts the concept of a purely fortuitous mutation, the clinamen, in which the atoms meet and group themselves together.

This was a type of dwarfism that resulted from a spontaneous mutation.

Ultraviolet gives us hereditary mutation and the euchromatin contains the genes that transmit heredity.

Most new genes that arise, either by mutation or reassortment or immigration, are quickly penalized by natural selection: the evolutionarily stable set is restored.

What counts are mutations in the gametes, the eggs and sperm cells, which are the agents of sexual reproduction.

And the first glob, you know, was itself a mutation, and against stiff statistical odds.

It was an enormous snow-white mutation derived from an arctic gyrfalcon the bird that indeed was reserved for kings.

A very slight variation in haplotype number, the kind of subtle, meaningless mutation that happened in the DNA of a germ cell.

Through green hyaline panels he could see the lift of the EAMH, the Experimental Applied Mutation Hospital, moving, leaving him here isolated.

Tools have always functioned as human prostheses, integrated into our bodies through our laboring practices as a kind of anthropological mutation both in individual terms and in terms of collective social life.

Accidentally useful mutations provide the working material for biological evolution-as, for example, a mutation for melanin in certain moths, which changes their color from white to black.