Dissimilation


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Dissimilation

 

in biology, the opposite of assimilation in the process of metabolism, consisting in the decomposition of organic compounds and conversion of protein, nucleic acids, fats, and carbohydrates (including those ingested) into simple substances. A number of dissimilation processes—respiration, fermentation, and glycolysis—play the central role in metabolism. As a result of these processes, energy contained in the molecules of complex organic compounds is released, partially to be transformed into adenosinephosphoric acids (chiefly ATP). The fundamental end products of dissimilation in all organisms are water, carbon dioxide, and ammonia. In animals these products are eliminated as they accumulate. In plant organisms CO2, partially, and NH3, totally, are used in the biosynthesis of organic matter, thus serving as the primary materials for assimilation.

The inseparable link between dissimilation and assimilation assures constant tissue renewal in organisms. Thus, in human blood one-half of the existing albumin is exchanged for new albumin molecules in ten days; the life span of erythrocytes is about four months. The relationship of the intensity of assimilation and dissimilation changes in relation to the stage of development, age, and physiological condition of the organism. The growth and development of the organism are characterized by the predominance of assimilation, which is manifested in the formation of new cells, tissues, and organs; their growth and differentiation; and in a general increase in body weight. In some pathological conditions and in starvation dissimilation usually predominates over assimilation, leading to a decrease in body weight.

S. E. SEVERIN and G. A. SOLOV’EVA


Dissimilation

 

in linguistics, one of the kinds of combinative sound changes in the course of speech. It occurs when one of two identical or similar speech sounds (adjacent or nonadjacent) changes to another distinct or less similar sound. Two examples of dissimilation are Latin peregrinum and Russian piligrim and Latinfebruaris and Russian fevral’.

References in periodicals archive ?
uru- is shown to have been analogically remodeled as a vowel-initial word on the basis of the feminine forms; uloka- had variant forms with and without the initial glide due to early dissimilation from the following *u and two rounded vowels *u.
In Juhan Liiv's trochee the dissimilation between the second and the third duration is more complicated.
And, of course, totalitarian ideologues are masters of deception, disinformation, dissimilation, propaganda, and lies (and, moreover, contemporary Islamists are able to take advantage of the theologically-sanctioned practice within Islam of taqiyya--dissimilation or lying to those Muslims consider enemies (49)).
Nord, Inter Science), The Main Pathways of Assimilation And Dissimilation of Nitrogen in Animals.
Associations, synagogues, and congregations are found to represent the same phenomenon of acculturation, assimilation, and dissimilation within the polis of the Greek East.
Two forms show apparent dissimilation (uCus [right arrow] uCuh [right arrow] uCeh); [puteh] 'snapped apart' (compare to putus) and [lu[gamma]eh] 'straight' (compare to lurus).
Dissimilation of tryptophan and related indolic compounds by ruminal microorganisms in vitro.
A dissimilation of the affricates first took place (*caca- > *caca-), after which there was a regular change *c > Fi s.
There also is evidence that dissimilation is generally anticipatory or root-controlled, hence subject to the same 3/4 situation.
That part of the grammar provides a description of Late Middle English shifts of quantity, including geminate simplification, metatheses, distant assimilation and dissimilation, various qualitative changes, including modifications of word-final homorganic clusters, loss of consonants with velar articulation ([x, 1, r]), continuations of earlier changes, haplology, transformations in the sequence consonant + [j] leading to the rise of new palatal sounds, loss of plosives in certain consonant sequences, loss of [h], modifications of the initial clusters with [w].
Should we read such moments as a strategic dissimilation of self, or what Sinfield calls a "confusion of gender categories" (Sinfield, p.