Carbohydrates are one of the widely discussed topics among students of science across the world and they are simply referred by names like disaccharides, monosaccharides, and polysaccharides or by terms like complex carbohydrates. There are different ways in which carbohydrates helps living beings like storing energy in the form of glycogen and starch. It helps in cell signalling as glycolipids and glycoproteins that act as determinants of blood groups. It helps in transporting energy to the muscles and the nervous system. This would mean every individual cell in particular other than the mainly chosen primary fuel molecule with particular differences on distinct cell types. Also, it acts as surface makers of cells, forms a part of nucleic acids like mRNA, tRNA, ribosome, and genes and so on. As far as humans are concerned, the carbohydrates that aid the metabolism are available in the form of starch and glycogen as alpha glycosidic bonds.
Dietary glucose is found aplenty in starch. Amalyses are the enzymes that degrade starch for assisting metabolism. Glucose has many sources such as lactose (from milk), fructose (from fruits), and sucrose (from table sugar). Active membrane transport systems aid the absorption of fructose, glucose, and fructose which are known by the name monosaccharide species. Monosaccharide components are formed by the division of disaccharides by special intestinal glucosidases. Glucose types like maltose are hydrolyzed by isomaltase with less ability to get desired results. Intolerance for lactose is caused by lactase deficiency – an enzyme which is needed to break down the lactose in milk and other dairy products.
As far as humans are concerned, there are no special requirements for carbohydrates excluding ascorbic acid and Vitamin C. Certain animals like primates, guinea pigs, and humans do not possess the necessary enzymes like that are necessary for the L-ascorbic acid synthesis. This is a metabolic disorder that is inborn and happens in the course of the evolution of primates. Hence, humans have to gather the same through food intake. The remaining monosaccharides are not necessary dietary supplements and could be synthesized as usual.
The small intestine contains intestinal mucosal cells that transport the monosaccharides into the circulatory system, where they move on into the liver. Here, the galactose and fructose are converted into glucose. The liver’s primary role is to regulate the levels of glucose in the blood, or in other words, act as a blood “glucostat”. Glucose molecules produced in excess are stored primarily in the liver and muscle cells as glycogen. It is also stored in the form of metabolized fat in adipocytes. Instead of fat, only glycogen would be used to maintain an adequate level of glucose in the bloodstream when food intake is restricted. Fat can be used for the oxidative regeneration of ATP and reductive power (NADH).
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