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why is glucose rather than sucrose given intravenously

Effect of acid and heat on sugar Sucrose (table sugar) is a disaccharide, meaning it is two simple sugars, glucose and fructose, that have reacted in such a wa
y that they join together, losing a molecule of water in the process. A reaction that produces water is called a condensation reaction. The fructose acts like an acid, and donates a proton. The glucose acts like a base, and donates a hydroxide ion. The proton and the hydroxide ion combine to form water, and the two simple sugars combine to form sucrose. The reverse reaction, called hydrolysis, is where a water molecule is added to a molecule to break it into two parts. Hydrolysis of sucrose in water happens very slowly all by itself.

But if an acid is added, it acts like a catalyst, promoting a faster reaction, but not getting used up in the process. Heating up the solution makes the reaction go even faster. The result of heating sucrose in water with a little lemon juice or vinegar in it is that much of the sucrose is converted into the two simple monosaccharides. Since fructose is a lot sweeter than sucrose, the result is a sweeter solution, even though glucose is not quite as sweet as sucrose. Since the acid is not used up, the solution is also a little tart, but that can be fixed by adding a weak base like egg whites or baking soda. If there are proteins in the solution, they can also react with the acid to neutralize it. -The medium contains 10 times as much lactose and sucrose as glucose.

Bacteria that ferment glucose produce a wide variety of acids, turning the color of the me dium from red to yellow. When any sugar is metabolized under anaerobic conditions (fermentation), there is increased acid production; thus the butt of the tube remains acid for a longer period of time. When glucose only is fermented, acid is produced throughout the medium but due to the relatively low concentration of glucose in the medium and the aerobic metabolism that is present on the slant, nitrogenous metabolic end products soon change the reaction of the slant to alkaline. These alkaline products neutralize the small amounts of acids present in the slant but are unable to neutralize the large amounts acid present in the butt.

Thus, the appearance of an alkaline (red) slant and an acid (yellow) butt after 24 hours incubation indicates that the organism is a glucose fermenter but is unable to ferment lactose and sucrose. Bacteria that ferment lactose or sucrose (or both), in addition to glucose, produce such large amounts of acid that the oxidative deamination of protein that may occur in the slant does not yield enough alkaline products to cause a reversion of pH in that region. Thus, these bacteria produce an acid slant and acid butt. - got it from the net too but my professor explained why

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