Monosaccharides glucose

Among the various types of sugars marketed, the mass consumption of sucrose far outweighs by volume the consumption of other products. Sucrose, also called table sugar, is a disaccharide which, upon hydrolysis, yields two monosaccharides glucose and fmctose. Various types of sugar vary in sweetness (1). 

Glucose/galactose malabsotption (GGM) is an intestinal monosaccharide (glucose and galactose) transport deficiency. The disorder manifests itself within the first weeks of life. The severe diarrhea and dehydration are usually fatal unless glucose and galactose are eliminated from the diet. Fiuctose and xylose are absorbed normally. Occurrence in both males and females, familial incidence, in particular in parental consanguinity, indicate autosomal recessive inheritance of... 

Fourteen DFAs and some oligomers were identified in caramel obtained by thermal treatment of inufin. - Monosaccharides (glucose, fructose), dehydration products (1,6-anhydro-p-D-glucopyranose, 1,6-anhydro-p-D-glucofuranose), disaccharides (gentiobiose and isomaltose), and oligosaccharides were also found in glucose and sucrose caramel. ... 

The monosaccharide glucose contains four asymmetric carbons carbons 2, 3, 4 and 5. A general formula for calculating the maximum number of stereoisomers is given by 2n, where n is the number of asymmetric carbons. For this compound, since n = 4, the maximum number of stereoisomers is 24 = 16. 

Fructose is found in honey and fruit and as part of the disaccharide sucrose (common table sugar). Sucrose is hydrolyzed by intestinal brush border sucrase, and the resulting monosaccharides, glucose and fructose, are absorbed into the portal blood. The liver phosphorylates frurtose and cleaves it into glyceraldehyde and DHAP. Smaller amounts are metabolized in renal proximal tubules. The pathway is shown in Figure 1-12-7 important enzymes to remember are ... 

Carbohydrates mainly occur in food in the form of polymers (starches and glycogen). They are cleaved by pancreatic amylase into oligosaccharides and are then hydrolyzed by glycosidases, which are located on the surface of the intestinal epithelium, to yield monosaccharides. Glucose and galactose are taken up into the enterocytes by secondary active cotransport with Na"" ions (see p. 220). In addition, monosaccharides also have passive transport systems in the intestine. 

Di-, tri- and tetrasaccharides These carbohydrates are dimers, trimers and tetramers of monosaccharides, and are formed from two, three or four monosaccharide molecules, with the elimination of one, two or three molecules of water. For example, sucrose is a disaccharide composed of two monosaccharides, glucose and fructose. 

Monosaccharides Glucose and fructose are the principal mono saccharides found in food. Glucose is abundant in fruits, sweet corn, corn syrup, and honey. Free fructose is found together with free glucose and sucrose in honey and fruits... 

Source and kinds of disaccharidases The final digestive processes occur at the mucosal lining of the small intestine. Several disaccharidases [for example, lactase (p-galactosidase), sucrase, maltase, and isomal-tase] produce monosaccharides (glucose, galactose, and fructose). These enzymes are secreted by and remain associated with the luminal side of the brush border membranes of intestinal mucosal cells. Absorption of the monosaccharides requires specific trans porters. 

Honey is a mixture of the monosaccharides glucose and fructose. Glucose is a six-membered ring, and fructose is a five-membered ring. For simplicity, the stick structures introduced in Chapter 12 are shown below each molecular model. 

How does the chemical structure of the monosaccharide glucose differ from that of the monosaccharide fructose ... 

Besides lactose, small amounts of other carbohydrates are found in milk, partly in a free form and partly bound to proteins, lipids, or phosphate. In some milks, other carbohydrates occur in higher concentrations than lactose (Jenness et al. 1964). Cows milk contains the monosaccharides glucose and galactose in concentrations of about 10 mg/10 ml (Reineccius et al. 1970) the amount of oligosaccharides is small, 100 mg/liter (Renner 1983). The review of Jenness and Sloan (1970) is an excellent reference for those interested in the evolutionary biochemistry of lactose. 

A study using whole-body calorimetry showed that there was no significant difference in net fat accumulation in lean or obese women when fed controlled excess of dietary energy supplied by the monosaccharides glucose and fructose, the disaccharide sucrose, or fat (McDevitt et al., 2000). 

The disaccharide lactose, is only found in milk and is hydrolysed with water in the presence of an enzyme lactase to form the monosaccharide glucose and galactose. This occurs in the small intestine. Some people, and particularly those from Eastern and African countries, are deficient in lactase so they are intolerant of milk. This can cause diarrhoea. Many African and Chinese foods do not include milk for this reason. 

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