O documento descreve os processos digestivos e absorção de nutrientes no trato gastrointestinal humano, incluindo a ação das enzimas digestivas na boca, estômago, intestino delgado e intestino grosso.
51. Ácidos graxos e outros produtos de degradação são captados pelas células da mucosa intestinal e reconvertidos em triacilgliceróis e transportados por quilomícrons.
52. ÁCIDOS GRAXOS Longas cadeias hidrocarbonadas com carboxila terminal. Constituinte dos lipídeos. Apresentam de 4 a 36 carbonos. Nomenclatura: Ex.: 20:2 ; 9,12 Os mais freqüentes possuem nº par de C, cadeia não-ramificada, duplas não conjugadas e duplas na configuração CIS.
77. a) nicotinamida adenina dinucleotídio (NAD+ e NADH) Aceita um íon hidrogênio e dois elétrons, o que equivale a um hidreto. NAD + + 2e - + 2H + --- NADH + H +
78. b) flavina adenina dinucleotídio ( FAD+ e FADH 2 ) Aceita um próton, além do íon hidreto. FAD + 2H + + 2e - --- FADH 2
79. Vitaminas do Complexo B Tiamina ou vitamina B1 Riboflaviana ou vitamina B2 Niacina ou vitamina B3 Adenina ou vitamina B4 Ácido Pantotênico ou vitamina B5 Piridoxina ou vitamina B6 Biotina ou vitamina B7 Ácido fólico ou vitamina B9 Cobalamina ou vitamina B12
80.
81. Riboflavina ou Vitamina B2 Riboflavina favorece o metabolismo dos lipídeos, carboidratos e proteínas. É necessária na síntese da flavina - adenina dinucleotídeo (FAD).
82. Niacina ou Vitamina B3 A designação "vitamina B 3 " também inclui a amida correspondente, ou seja a nicotinamida ou niacinamida.
FIGURE 7-14a Glycogen and starch. (a) A short segment of amylose, a linear polymer of D -glucose residues in ( α 1 -> 4) linkage. A single chain can contain several thousand glucose residues. Amylopectin has stretches of similarly linked residues between branch points. Glycogen has the same basic structure, but has more branching than amylopectin.
FIGURE 7-22 (part 1a) Repeating units of some common glycosaminoglycans of extracellular matrix. The molecules are copolymers of alternating uronic acid and amino sugar residues (keratan sulfate is the exception), with sulfate esters in any of several positions, except in hyaluronan. The ionized carboxylate and sulfate groups (red in the perspective formulas) give these polymers their characteristic high negative charge. Therapeutic heparin contains primarily iduronic acid (IdoA) and a smaller proportion of glucuronic acid (GlcA, not shown), and is generally highly sulfated and heterogeneous in length. The space-filling model shows a heparin segment as its solution structure, as determined by NMR spectroscopy (PDB ID 1HPN). The carbons in the iduronic acid sulfate are colored blue; those in glucosamine sulfate are green. Oxygen and sulfur atoms are shown in their standard colors of red and yellow, respectively. The hydrogen atoms are not shown (for clarity). Heparan sulfate (not shown) is similar to heparin but has a higher proportion of GlcA and fewer sulfate groups, arranged in a less regular pattern.
FIGURE 7-22 (part 1b) Repeating units of some common glycosaminoglycans of extracellular matrix. The molecules are copolymers of alternating uronic acid and amino sugar residues (keratan sulfate is the exception), with sulfate esters in any of several positions, except in hyaluronan. The ionized carboxylate and sulfate groups (red in the perspective formulas) give these polymers their characteristic high negative charge. Therapeutic heparin contains primarily iduronic acid (IdoA) and a smaller proportion of glucuronic acid (GlcA, not shown), and is generally highly sulfated and heterogeneous in length. The space-filling model shows a heparin segment as its solution structure, as determined by NMR spectroscopy (PDB ID 1HPN). The carbons in the iduronic acid sulfate are colored blue; those in glucosamine sulfate are green. Oxygen and sulfur atoms are shown in their standard colors of red and yellow, respectively. The hydrogen atoms are not shown (for clarity). Heparan sulfate (not shown) is similar to heparin but has a higher proportion of GlcA and fewer sulfate groups, arranged in a less regular pattern.
FIGURE 7-27 Proteoglycan aggregate of the extracellular matrix. Schematic drawing of a proteoglycan with many aggrecan molecules. One very long molecule of hyaluronan is associated noncovalently with about 100 molecules of the core protein aggrecan. Each aggrecan molecule contains many covalently bound chondroitin sulfate and keratan sulfate chains. Link proteins at the junction between each core protein and the hyaluronan backbone mediate the core protein – h yaluronan interaction. The micrograph shows a single molecule of aggrecan, viewed with the atomic force microscope (see Box 11-1).
FIGURE 7-28 Interactions between cells and the extracellular matrix. The association between cells and the proteoglycan of the extracellular matrix is mediated by a membrane protein (integrin) and by an extracellular protein (fibronectin in this example) with binding sites for both integrin and the proteoglycan. Note the close association of collagen fibers with the fibronectin and proteoglycan.
FIGURE 7-29 Oligosaccharide linkages in glycoproteins. (a) O -linked oligosaccharides have a glycosidic bond to the hydroxyl group of Ser or Thr residues (pink), illustrated here with GalNAc as the sugar at the reducing end of the oligosaccharide. One simple chain and one complex chain are shown. (b) N -linked oligosaccharides have an N -glycosyl bond to the amide nitrogen of an Asn residue (green), illustrated here with GlcNAc as the terminal sugar. Three common types of oligosaccharide chains that are N -linked in glycoproteins are shown. A complete description of oligosaccharide structure requires specification of the position and stereochemistry ( α or β ) of each glycosidic linkage.