stereoisomers of each other. When starch and cellulose undergo strong hydrolysis “by means of particular enzymes or through the action of acids” and the carbon chain is broken, the reaction will procure D-glucose. This D-glucose molecule is the basic unit of the macromolecular structure. Starch and cellulose are both polysaccharides, or polymers, of glucose. Despite having similar molecular structures, starch and cellulose have many differing properties. Starch is easily digested by humans whereas cellulose is indigestible. When hydrolyzed β-glucose yields cellobiose from cellulose and α-glucose yields maltose from starch. β- and α-glucose are diastereomers. In these pairs of polymers, the chemical structure of the monomeric units is the same. The difference of the polymers lies within the substituents on the molecules, whether they are “cis of trans in the hydrocarbon polymers, and equatorial or axial in cellulose and starch.” Definitions Many definitions that describe a specific conformer (IUPAC Gold Book) exist, developed by William Klyne and Vladimir Prelog, constituting their Klyne–Prelog system of nomenclature: a torsion angle of ±60° is called gauche a torsion angle between 0° and ±90° is called syn (s) a torsion angle between ±90° and 180° is called anti (a) a torsion angle between 30° and 150° or between –30° and –150° is called clinal a torsion angle between 0° and 30° or 150° and 180° is called periplanar (p) a torsion angle between 0° to 30° is called synperiplanar or syn- or cis-conformation (sp) a torsion angle between 30° to 90° and –30° to –90° is called synclinal or gauche or skew (sc) a torsion angle between 90° to 150°, and –90° to –150° is called anticlinal (ac) a torsion angle between ±150° to 180° is called antiperiplanar or anti or trans (ap). Torsional strain results from resistance to twisting about a bond. Types AtropisomerismAn energetic form of axial chirality. This form of chirality derives from differential substitution about a bond, commonly between two sp²-hydridized atoms. Cis–trans isomerismAlso referred to as geometric isomers, these compounds have different configurations due to the inflexible structure of the molecule. Two requirements must be met for a molecule to present cis-trans isomerism:1. Rotation within the molecule must be restricted.2. Two nonidentical groups must be on each doubly bonded carbon atom. Conformational isomerismThis form of isomerism is also referred to as conformers, rotational isomers, and rotamers. Conformational isomerism is produced by rotation about the Single bond. DiastereomersThese stereoisomers are non-image,