There are many calculations that have been done using ab-initio quantum methods applied to fullerenes. Trimetaspheres have the potential for use in diagnostics as safe imaging agents , therapeutics  and in organic solar cells. Fullerites are the solid-state manifestation of fullerenes and related compounds and materials. An improbable, egg-shaped endohedral fullerene that violates the isolated pentagon rule". In the strict sense, " sugar " is applied for sweet, soluble carbohydrates, many of which are used in food. The C 72 structure is also in this class, but the endohedral version with a trapped lanthanide -group atom is soluble due to the interaction of the metal atom and the electronic states of the fullerene. Following a diet consisting of very low amounts of daily carbohydrate for several days will usually result in higher levels of blood ketone bodies than an isocaloric diet with similar protein content.
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Although there are numerous kinds of disaccharides, a handful of disaccharides are particularly notable. Sucrose , pictured to the right, is the most abundant disaccharide, and the main form in which carbohydrates are transported in plants. It is composed of one D-glucose molecule and one D-fructose molecule. Lactose , a disaccharide composed of one D-galactose molecule and one D-glucose molecule, occurs naturally in mammalian milk.
Disaccharides can be classified into two types: If the functional group is present in bonding with another sugar unit, it is called a reducing disaccharide or biose. Carbohydrate consumed in food yields 3. Lower amounts of carbohydrate are usually associated with unrefined foods, including beans, tubers, rice, and unrefined fruit. Organisms typically cannot metabolize all types of carbohydrate to yield energy.
Glucose is a nearly universal and accessible source of energy. Many organisms also have the ability to metabolize other monosaccharides and disaccharides but glucose is often metabolized first. In Escherichia coli , for example, the lac operon will express enzymes for the digestion of lactose when it is present, but if both lactose and glucose are present the lac operon is repressed, resulting in the glucose being used first see: Polysaccharides are also common sources of energy.
Many organisms can easily break down starches into glucose; most organisms, however, cannot metabolize cellulose or other polysaccharides like chitin and arabinoxylans. These carbohydrate types can be metabolized by some bacteria and protists. Ruminants and termites , for example, use microorganisms to process cellulose. Even though these complex carbohydrates are not very digestible, they represent an important dietary element for humans, called dietary fiber.
Fiber enhances digestion, among other benefits. Nutritionists often refer to carbohydrates as either simple or complex. However, the exact distinction between these groups can be ambiguous. The term complex carbohydrate was first used in the U.
Senate Select Committee on Nutrition and Human Needs publication Dietary Goals for the United States where it was intended to distinguish sugars from other carbohydrates which were perceived to be nutritionally superior.
This confusion persists as today some nutritionists use the term complex carbohydrate to refer to any sort of digestible saccharide present in a whole food, where fiber, vitamins and minerals are also found as opposed to processed carbohydrates, which provide energy but few other nutrients. The standard usage, however, is to classify carbohydrates chemically: In any case, the simple vs. The speed of digestion is determined by a variety of factors including which other nutrients are consumed with the carbohydrate, how the food is prepared, individual differences in metabolism, and the chemistry of the carbohydrate.
The USDA's Dietary Guidelines for Americans call for moderate- to high-carbohydrate consumption from a balanced diet that includes six one-ounce servings of grain foods each day, at least half from whole grain sources and the rest from enriched. The glycemic index GI and glycemic load concepts have been developed to characterize food behavior during human digestion. They rank carbohydrate-rich foods based on the rapidity and magnitude of their effect on blood glucose levels.
Glycemic index is a measure of how quickly food glucose is absorbed, while glycemic load is a measure of the total absorbable glucose in foods. The insulin index is a similar, more recent classification method that ranks foods based on their effects on blood insulin levels, which are caused by glucose or starch and some amino acids in food.
Carbohydrates are a common source of energy in living organisms; however, no single carbohydrate is an essential nutrient in humans. Following a diet consisting of very low amounts of daily carbohydrate for several days will usually result in higher levels of blood ketone bodies than an isocaloric diet with similar protein content.
This relatively high level of ketone bodies is commonly known as ketosis and is very often confused with the potentially fatal condition often seen in type 1 diabetics known as diabetic ketoacidosis.
Somebody suffering ketoacidosis will have much higher levels of blood ketone bodies along with high blood sugar, dehydration and electrolyte imbalance. Long-chain fatty acids cannot cross the blood—brain barrier , but the liver can break these down to produce ketones. However, the medium-chain fatty acids octanoic and heptanoic acids can cross the barrier and be used by the brain, which normally relies upon glucose for its energy. Carbohydrate metabolism denotes the various biochemical processes responsible for the formation , breakdown and interconversion of carbohydrates in living organisms.
The most important carbohydrate is glucose , a simple sugar monosaccharide that is metabolized by nearly all known organisms. Glucose and other carbohydrates are part of a wide variety of metabolic pathways across species: Plant components are consumed by animals and fungi , and used as fuel for cellular respiration. Catabolism is the metabolic reaction which cells undergo to break down larger molecules, extracting energy. There are two major metabolic pathways of monosaccharide catabolism: The monosaccharide units can then enter into monosaccharide catabolism.
Carbohydrate chemistry is a large and economically important branch of organic chemistry. Some of the main organic reactions that involve carbohydrates are:.
From Wikipedia, the free encyclopedia. This is the latest accepted revision , reviewed on 6 September This article may lend undue weight to certain ideas, incidents, or controversies. Please help improve it by rewriting it in an neutral presentation that contextualizes different points of view. June Learn how and when to remove this template message. Human Biology and Health. Englewood Cliffs, New Jersey: International Journal of Obesity. Introduction to Biochemistry 2nd ed. A Textbook of Botany for Colleges and Universities.
Tietz fundamentals of clinical chemistry. Carbohydrates in human nutrition. Food and Agriculture Organization of the United Nations. Essentials of Glycobiology 3rd ed. Cold Spring Harbor NY: Cold Spring Harbor Laboratory Press. Stereochemistry of the Monosaccharides". In Pigman and Horton. Chemistry and Biochemistry Vol 1A 2nd ed. Mutarotations and Actions of Acids and Bases". Retrieved October 30, The Journal of Nutrition.
The American Journal of Clinical Nutrition. The National Academies Press. Harvard School of Public Health. Retrieved April 3, Archives of Internal Medicine. The Journal of Neuroscience. Journal of Cerebral Blood Flow and Metabolism. Metabolism , catabolism , anabolism. Metabolic pathway Metabolic network Primary nutritional groups. Pentose phosphate pathway Fructolysis Galactolysis. Photosynthesis Anoxygenic photosynthesis Chemosynthesis Carbon fixation. Fatty acid degradation Beta oxidation Fatty acid synthesis.
Steroid metabolism Sphingolipid metabolism Eicosanoid metabolism Ketosis Reverse cholesterol transport. Amino acid synthesis Urea cycle. Purine metabolism Nucleotide salvage Pyrimidine metabolism.
Metal metabolism Iron metabolism Ethanol metabolism. Aldose Ketose Furanose Pyranose. Anomer Cyclohexane conformation Mutarotation. Aldotriose Glyceraldehyde Ketotriose Dihydroxyacetone. Aldotetroses Erythrose Threose Ketotetrose Erythrulose.
Many of these methods have been developed to analyze for microcystins and its congeners, however, relatively little work has been done on methods for detection of other toxins, including anatoxins and cylindrospermopsins. Saxitoxins are the exception, as they also occur widely in the marine environment and many methods have been developed for their detection in shellfish.
Analytical methods such as enzyme—linked immunosorbent assays ELISA already exist to analyze cyanobacterial hepatotoxins and saxitoxins, and the protein phosphatase inhibition assay PPIA can be used for microcystins. These two methods are sensitive, rapid, and suitable for large-scale screening but are predisposed to false positives and unable to differentiate between toxin variants.
However, relatively little work has been done on methods for detection of other toxins, including anatoxins and cylindrospermopsins. The following table describes the methods available for cyanotoxin measurement in freshwater. Geological Survey and Ann St. Available for this toxin 0: Unavailable for this toxin. FR, Foundation for Water Research. In the case of public waterways and drinking water sources, many state environmental agencies operate monitoring, sampling, and testing programs.
Several of these states perform the necessary detection analysis on samples taken from potential HABs in state-run laboratories; however, many states with HAB programs, in addition to municipalities, private utilities, and other riparian stakeholders of freshwater systems send their samples to commercial and public laboratories.
For a non-comprehensive list of laboratories that accept samples for cyanobacteria and cyanotoxin analysis, please visit the State Resources page on this website. For comments, feedback or additional information, please contact Lesley D'Anglada Danglada. Contact Us to ask a question, provide feedback, or report a problem. Jump to main content. An official website of the United States government. Nutrient Policy and Data. What detection methods are available for cyanobacteria and cyanotoxins in water?
Initial detection of freshwater HAB events relies on qualitative, visual observations. The tell-tale manifestations of a HAB include:. Useful as a screening tool; relatively simple to use and is highly sensitive, with low detection limits relative to any current guideline values. Currently, there is no commercial kit available.