CHEMISTRY GLOSSARY

phenylalanine    →   fenilalanin

Phenylalanine is hydrophobic amino acids with aromatic side chain. It is quite hydrophobic and even the free amino acid is not very soluble in water. Phenylalanine is large aromatic residue that is normally found buried in the interior of a protein and is important for protein stability. It is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested.

• Abbreviations: Phe, F
• IUPAC name: 2-amino-3-phenylpropanoic acid
• Molecular formula: C₉H₁₁NO₂
• Molecular weight: 165.19 g/mol

plastic    →   plastika

Plastic is a material that can be shaped by the application of heat or pressure. Most are based on synthetic polymers although some are the product of natural substances (such as cellulose derivatives, but excluding the rubbers.). They are usually light and permanent solids, being also heat and electric isolators. If the materials soften again when reheated, they are said to be thermoplastic. If, after fashioning, they resist further applications of heat, they are said to be thermoset.

polymer    →   polimer

Polymer is a substance composed of molecules of high relative molecular mass (molecular weight), the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass (monomers). In most cases the number of monomers is quite large and is often not precisely known. A single molecule of a polymer is called a macromolecule. Polystyrene is light solid material obtained by polymerisation of styrene (vinyl benzene).

polysaccharide    →   polisaharid

Polysaccharides are compounds consisting of a large number of simple sugars (monosaccharides) linked together by glycosidic bonds. When polysaccharides are composed of a single monosaccharide building block, they are termed homopolysaccharides. Heteropolysaccharides contain two or more different types of monosaccharide. Polysaccharides may have molecular weights of up to several million and are often highly branched. Since they have only the one free anomeric -OH group at the end of a very long chain, polysaccharides aren’t reducing sugars and don’t show noticeable mutarotation. The most common polysaccharides are cellulose, starch, and glycogen.

porphyrin    →   porfirin

Porphyrin is a planar ligand with a central ring structure and various substituent groups at the edges of the ring.

potential energy    →   potencijalna energija

Potential energy (E_p) is the energy stored in a body or system as a consequence of its position, shape, or state (this includes gravitation energy, electrical energy, nuclear energy, and chemical energy). Gravitational potential energy is the energy associated with the state of separation between bodies that attracts each other via gravitational force. Elastic potential energy is the energy associated with the state of compression or extension of an elastic object. Thermal energy is associated with the random motions of atoms and molecules in a body.

proline    →   prolin

Proline has an aliphatic side chain with a distinctive cyclic structure. It is unusual because it is conformationally restricted. The secondary amino (imino) group of proline residues is held in a rigid conformation that reduces the structural flexibility of polypeptide regions containing proline. It is not an essential amino acid, which means that the human body can synthesize it.

• Abbreviations: Pro, P
• IUPAC name: pyrrolidine-2-carboxylic acid
• Molecular formula: C₅H₉NO₂
• Molecular weight: 115.13 g/mol

retardation factor    →   faktor zaostajanja

Retardation factor, R_F, (in planar chromatography) is a ratio of the distance travelled by the centre of the spot to the distance simultaneously travelled by the mobile phase:

The R_F value is characteristic for any given compound on the same stationary phase using the same mobile phase for development of the plates. Hence, known R_F values can be compared to those of unknown substances to aid in their identifications.

rhombohedral crystal system    →   romboedarski kristalni sustav

Rhombohedral crystal system is also known as the trigonal system. The crystallographic axes used in this system are of equal length. None of the axes are perpendicular to any other axis.

rhombohedral lattice    →   romboedarska rešetka

Rhombohedral (or trigonal) lattice has one lattice point at the each corner of the unit cell. It has unit cell vectors a=b=c and interaxial angles α=β=γ≠90°.