Aula 30 - Monossacarídeos: Glicose C6H12O6 - Parte 1

Carbohydrates, also called hydrates of carbon, generally have the molecular formula (CH2O)n. The simplest carbohydrates are monosaccharides. Examples of monosaccharides in the human diet: Glucose, fructose, and galactose, known as sugars. Glucose is a polyhydroxyaldehyde; the molecule has an aldehyde functional group, hence the name aldose. Glucose is classified according to the number of carbons: Hexose (6 carbons). A chiral, or asymmetric, carbon is a saturated carbon (with four single bonds) that has four different ligands. To classify a carbon as chiral, the entire set of atoms present after the bond must be considered the ligand. Monosaccharides can be divided into two groups, which differ in the configuration of the chiral center furthest from the carbonyl carbon. When the hydroxyl group of the reference carbon is on the right (dextro) in a projection formula that presents the carbonyl carbon at the top, the sugar is the D-isomer; when it is on the left (levo), it is the L-isomer. Most hexoses in living organisms are D-isomers. In the glucose molecule, the chiral carbon farthest from carbon 1 (carbonyl) is carbon 5. If the hydroxyl group attached to this carbon is on the right, the molecule is D-glucose; if it is on the left, it is L-glucose. References: USBERCO, J.; SALVADOR, E. Chemistry, single volume. 5th ed. São Paulo: Saraiva, 2002, part 3, unit 24, p. 559-60. MARZZOCO, A.; TORRES, B. B. Basic Biochemistry. 2nd ed. Rio de Janeiro: Guanabara Koogan, 1999, part 2, chap. 6, pp. 91-2. Nelson L. D.; Cox M. M. Lehninger's Principles of Biochemistry. 6th ed. São Paulo: artmed editora LTDA, 2014, chap. 7, pp. 243-56.