Word Finder - polymorphism

definition

The ability to assume different forms or shapes.

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The coexistence, in the same locality, of two or more distinct forms independent of sex, not connected by intermediate gradations, but produced from common parents.

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The feature pertaining to the dynamic treatment of data elements based on their type, allowing for an instance of a method to have several definitions.

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(type theory) The property of certain typed formal systems of allowing for the use of type variables and binders/quantifiers over those type variables; likewise, the property of certain expressions (within such typed formal systems) of making use of at least one such typed variable.

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The ability of a solid material to exist in more than one form or crystal structure; pleomorphism.

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The regular existence of two or more different genotypes within a given species or population; also, variability of amino acid sequences within a gene's protein.

This temperature is somewhat different from the ordinary melting-point, the latter corresponding to atmospheric pressure, the former to the maximum vapour-pressure; and so we come to a third relation for polymorphism.

While, therefore, there is much evidence of a negative character against the existence of an extensive polymorphism among algae, some amount of metamorphosis is known to occur.

The development of the theory of crystal structure, and the fundamental principles on which is based the classification of crystal forms, are treated in the article Crystallography; in the same place will be found an account of the doctrine of isomorphism, polymorphism and morphotropy.

Isomorphism may be defined as the existence of two or more different substances in the same crystal form and structure, polymorphism as the existence of the same substance in two or more crystal modifications, and morphotropy (after P. von Groth) as the change in crystal form due to alterations in the molecule of closely (chemically) related substances.

While polysymmetry is solely conditioned by the manner in which the mimetic twin is built up from the single crystals, there being no change in the scalar properties, and the vector properties being calculable from the nature of the twinning, in the case of polymorphism entirely different structures present themselves, both scalar and vector properties being altered; and, in the present state of our knowledge, it is impossible to foretell the characters of a polymorphous modification.

It is on clinical grounds that beriberi, scarlet fever, measles, &c., are recognized as belonging to the same class, and evolving in phases which differ not in intimate nature but in the more superficial and inessential characters of time, rate and polymorphism; and the impression is gaining strength that acute rheumatism belongs to the group of the infections, certain sore throats, chorea and other apparently distinct maladies being terms of this series.

Polymorphism usually occurs, certain individuals having the form of avicularia or vibracula.

These laws have the advantage of being applicable to the mutual transformations of isomers, whatever be the nature of the deeper origin, and so bring polymerism, metamerism and polymorphism together.

The study of polymorphism has been especially pursued by Otto Lehmann, who proved that it is an almost general property; the variety of forms which a given substance may show is often great, ammonium nitrate, for instance, showing at least four of them before melting.

Poulton, in an admirable discussion of contemporary views regarding species (presidential address to the Entomological Society of London 1904), has shown that Darwin did not believe in the objective existence of species, not only because he was led to discard the hypothesis of special creation as the explanation of the polymorphism of life, but because in practice as a working systematist he could neither find for himself nor ascertain from other systematists any settled criteria by which a group of specimens could be elevated into a genus, accepted as a species, or regarded as a variety.

Chodat does not find so general a polymorphism, but nevertheless holds that Raphidium passes through stages represented by Protococcus, Characium, Dactylococcus and Sciadium.

Worker caste polymorphism has a genetic basis in a leaf-cutting ant.

In polymorphism, the taxonomic classification of species does not always match up with a tight genetic definition.

The p53 gene mutation was detected by fluorescence-based polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) methods.

Feline leucocyte antigen class II polymorphism and susceptibility to feline infectious peritonitis.

For these strains other typing methods that detect genetic polymorphism are now available.

Single strand conformational polymorphism (SSCP) analysis and direct sequencing of TSG101 cDNAs also identified no mutations or deletions.

This type of polymorphism is sometimes called parametric polymorphism.

This is most likely to be due to genetic polymorphism.

In addition an extensive search was made for other studies relating to ace gene polymorphism and renal damage.

To contrast, functional languages gain polymorphism through the use of first-class functions.

Low levels of nucleotide polymorphism within species coincided with low rates of recombination.

The method is called single-stranded conformation polymorphism (SSCP ).

One of the most interesting features of ant-societies is the dimorphism or polymorphism that may often be seen among the workers, the same species being represented by two or more forms. Thus the British " wood ant " (Formica rufa) has a smaller and a larger race of workers (" minor " and " major " forms), while in Ponera we find a blind race of workers and another race provided with eyes, and in Atta, Eciton and other genera, four or five forms of workers are produced, the largest of which, with huge heads and elongate trenchant mandibles, are known as the " soldier " caste.

Broadly this phenomenon is termed polymorphism; however, it is necessary to examine closely the diverse crystal modifications in order to determine whether they are really of different symmetry, or whether twinning has occasioned the apparent difference.

Amplified products will be digested by restriction enzymes in order to identify existing polymorphism.

It also discovered a single letter change in the genetic code, single nucleotide polymorphism (SNP).

If our knowledge of the life-histories of these organisms were perfect, their polymorphism would present no difficulties to classification; but unfortunately this is far from being the case.