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Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a speciation event (orthologs), or a duplication event (paralogs), or else a horizontal (or lateral) gene ...
Fractional crystallisation can be used to obtain pure para product, relying on the principle that it is less soluble than the ortho and thus will crystallise first. Care must be taken to avoid cocrystallisation of the ortho isomer. [2] Many nitro compounds' ortho and para isomers have quite different boiling points. These isomers can often be ...
The ratio between numbers of ortho and para molecules is about 3:1 at standard temperature where many rotational energy levels are populated, favoring the ortho form as a result of thermal energy. However, at low temperatures only the J = 0 level is appreciably populated, so that the para form dominates at low temperatures (approximately 99.8% ...
In biology, homology is similarity in anatomical structures or genes between organisms of different taxa due to shared ancestry, regardless of current functional differences. Evolutionary biology explains homologous structures as retained heredity from a common ancestor after having been subjected to adaptive modifications for different ...
Neofunctionalization is the process by which a gene acquires a new function after a gene duplication event. The figure shows that once a gene duplication event has occurred one gene copy retains the original ancestral function (represented by the green paralog), while the other acquires mutations that allow it to diverge and develop a new function (represented by the blue paralog).
English: Top: An ancestral gene duplicates to produce two paralogs (histone H1.1 and 1.2).A speciation event produces orthologs in the two daughter species (human and chimpanzee).
Subfunctionalization is a neutral mutation process in which each paralog retains a subset of its original ancestral function. The figure illustrates that the ancestral gene (orange & blue) is capable of both functions before gene duplication. After gene duplication the functional capabilities are divided amongst the gene copies.
In addition to o-cymene, there are two other geometric isomers called m-cymene, in which the alkyl groups are meta-substituted, and p-cymene, in which they are para-substituted.