#isomer

• Allochlorophyll — An isomeric form of chlorophyll, obtained artificially or arising through minor chemical and structural alteration of the natural green pigment in plant or algal cells. This organic compound retains its basic properties in capturing the light spectrum, but exhibits modifications in the molecular structure of the porphyrin ring, being studied in plant physiology laboratories to understand the stability of the photosynthesis process.
• Allelotropism — A chemical and physical phenomenon consisting of the coexistence of two isomeric or tautomeric forms of the same substance in a reversible dynamic equilibrium, such that one form continuously transforms into the other, their ratio being dependent on external factors like temperature. Structurally, allelotropism represents a particular form of dynamic isomerism frequently encountered in advanced organic chemistry.
• Alloisomerism — A particular type or atypical form of isomerism in which chemical substances possess the same crude molecular formula and the same fundamental bonds, but differ structurally through spatial orientation, geometric configuration of substituents, or alternative atomic arrangement. This phenomenon causes significant differences in the physical, chemical, and biological properties of the respective compounds, being essential in drug synthesis.
• Aminophenol — A bifunctional organic compound with amphoteric character, derived from phenol by replacing a hydrogen atom on the aromatic ring with an amino group (-NH2). It has three positional isomers (ortho, meta, and para), of which para-aminophenol is the most industrially important, serving as a key structural intermediate in the synthesis of paracetamol, hair dyes, and photographic developers.
• Anisidine — An organic aromatic compound belonging to the amine family, derived from anisole and existing as three positional isomers (ortho, meta, and para); methoxyaniline. Industrially, it is used as an essential intermediate in the synthesis of azo dyes, pigments, and pharmaceuticals. In food biochemistry, p-anisidine is a primary reagent used to measure the secondary oxidation value of fats and oils by quantifying aldehyde formations.
• Anisomer — An asymmetric isomer or a compound substance formed by molecules whose segments or atomic groups do not present an equal ratio of geometric, structural, or molecular mass symmetry. As an adjective, it describes a state, chemical bond, or macromolecular process characterized by the inequality of components or polymeric segments, causing divergent physico-chemical properties.
• Anisomerogamy — A type of primitive sexual reproduction where fusion occurs between motile gametes that are unequal in size but similar in external structural shape. It represents an intermediate phase in the evolution of cellular reproduction, situated between isogamy (identical gametes) and oogamy (totally differentiated gametes), providing an initial functional differentiation between the smaller male and larger female sex cells.
• Arabinose — A monosaccharide containing five carbon atoms belonging to the pentose class, frequently encountered in the plant kingdom as a major structural component of complex polysaccharides in cell walls, such as plant gums, pectins, and hemicelluloses. Unlike most natural sugars that occur predominantly as the D-isomer, arabinose is notable because its L-isomer is the most widespread and biologically active form in nature.