20. Catabolism of proteins, polysaccharides, and lipids produces glucose, pyruvate, or intermediates of the tricarboxylic acid (TCA) cycle and, ultimately, energy in the form of adenosine triphosphate (ATP) or the reduced form of nicotinamide-adenine dinucleotide (NADH).

21. http://www.profesorenlinea.cl/imagenciencias/energiavivos10.png Glucólisis

22. http://www.biolaster.com/rendimiento_deportivo/metabolismo_energetico/anaerobico_lactico/glucolisis_anaerobicaD.jpg

23. Fermentation of pyruvate by different microorganisms results in different end products. The clinical laboratory uses these pathways and end products as a means of distinguishing different bacteria.

24. http://www.educa.aragob.es/iescarin/depart/biogeo/varios/BiologiaCurtis/Seccion%202/8-10.jpg Ciclo de Krebs

25. Electron transport chain, showing sequential oxidation and energy-generating steps. Electron transfer is accompanied by the flow of protons (H + ) from NADH, through coenzyme Q (CoQ), and electrons through the cytochromes (CYTO). Three ATPs are formed per molecule of NADH reoxidized, but only two ATPs are formed per molecule of FADH 2 reoxidized. FMN, flavin mononucleotide. (Modified from Slots J, Taubman MA, editors: Contemporary oral microbiology and immunology, St Louis, 1992, Mosby.)

26. Metabolismo aerobio de la glucosa.

27. SISNTESIS DEL PEPTIDOGLICANO

28. Peptidoglycan synthesis. A, Peptidoglycan synthesis occurs in the following three phases: (1) Peptidoglycan is synthesized from prefabricated units constructed and activated for assembly and transport inside the cell. (2) At the membrane the units are assembled onto the undecaprenol phosphate conveyor belt, and fabrication is completed. (3) The unit is translocated to the outside of the cell, where it is attached to the polysaccharide chain, and the peptide is cross-linked to finish the construction. Such a construction can be compared with the assembly of a space station. B, The cross-linking reaction is a transpeptidation. One peptide bond (produced inside the cell) is traded for another (outside the cell) with the release of d-alanine. The enzymes that catalyze the reaction are called d- alanine, d- alanine transpeptidase-carboxypeptidases. These enzymes are the targets of β-lactam antibiotics and are called penicillin-binding proteins. (© American Society of Clinical Pathologists. Reprinted with permission.)