Classification of carbohydrates

Objectives After completing this section, you should be able to • classify a specific carbohydrate as being a monosaccharide, disaccharide, trisaccharide, etc., given the structure of the carbohydrate or sufficient information about its structure. • classify a monosaccharide according to the number of carbon atoms present and whether it contains an aldehyde or ketone group. What Are Carbohydrates? The most abundant biomolecules on earth are carbohydrates. From a chemical viewpoint, carbohydrates are primarily a combination of carbon and water, and many of them have the empirical formula (CH 2O) n, where n is the number of repeated units. This view represents these molecules simply as “hydrated” carbon atom chains in which water molecules attach to each carbon atom, leading to the term “carbohydrates.” Although all carbohydrates contain carbon, hydrogen, and oxygen, there are some that also contain nitrogen, phosphorus, and/or sulfur. Carbohydrates have myriad different functions. They are abundant in terrestrial ecosystems, many forms of which we use as food sources. These molecules are also vital parts of macromolecular structures that store and transmit genetic information (i.e., DNA and RNA). They are the basis of biological polymers that impart strength to various structural components of organisms (e.g., cellulose and chitin), and they are the primary source of energy storage in the form of starch and glycogen. Monosaccharides In biochemistry, carbohydrates are often ...

\( \newcommand\) group at the 2-carbon. Contributors and Attributions John D. Robert and Marjorie C. Caserio (1977) Basic Principles of Organic Chemistry, second edition. W. A. Benjamin, Inc. , Menlo Park, CA. ISBN 0-8053-8329-8. This content is copyrighted under the following conditions, "You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format."

Dietary carbohydrates are a group of chemically defined substances with a range of physical and physiological properties and health benefits. As with other macronutrients, the primary classification of dietary carbohydrate is based on chemistry, that is character of individual monomers, degree of polymerization (DP) and type of linkage (α or β), as agreed at the Food and Agriculture Organization/World Health Organization Expert Consultation in 1997. This divides carbohydrates into three main groups, sugars (DP 1–2), oligosaccharides (short-chain carbohydrates) (DP 3–9) and polysaccharides (DP ⩾10). Within this classification, a number of terms are used such as mono- and disaccharides, polyols, oligosaccharides, starch, modified starch, non-starch polysaccharides, total carbohydrate, sugars, etc. While effects of carbohydrates are ultimately related to their primary chemistry, they are modified by their physical properties. These include water solubility, hydration, gel formation, crystalline state, association with other molecules such as protein, lipid and divalent cations and aggregation into complex structures in cell walls and other specialized plant tissues. A classification based on chemistry is essential for a system of measurement, predication of properties and estimation of intakes, but does not allow a simple translation into nutritional effects since each class of carbohydrate has overlapping physiological properties and effects on health. This dichotomy has led...

Key Terms Make certain that you can define, and use in context, the key terms below. • aldose • disaccharide • ketose • monosaccharide (simple sugar) • polysaccharide Carbohydrates are the most abundant class of organic compounds found in living organisms. They originate as products of photosynthesis, an endothermic reductive condensation of carbon dioxide requiring light energy and the pigment chlorophyll. \[ nCO_2 + n H_2O + Energy \rightarrow C_nH_O_n + nO_2\] As noted here, the formulas of many carbohydrates can be written as carbon hydrates, \(C_n(H_2O)_n\), hence their name. The carbohydrates are a major source of metabolic energy, both for plants and for animals that depend on plants for food. Aside from the sugars and starches that meet this vital nutritional role, carbohydrates also serve as a structural material (cellulose), a component of the energy transport compound ATP/ADP, recognition sites on cell surfaces, and one of three essential components of DNA and RNA. Carbohydrates are called saccharides or, if they are relatively small, sugars. Several classifications of carbohydrates have proven useful, and are outlined in the following table. Complexity Simple Carbohydrates monosaccharides Complex Carbohydrates disaccharides, oligosaccharides & polysaccharides Size Tetrose C 4 sugars Pentose C 5 sugars Hexose C 6 sugars Heptose C 7 sugars etc. C=O Function Aldose sugars having an aldehyde function or an acetal equivalent. Ketose sugars having a ketone function o...

Food is one of life’s greatest pleasures. It offers amazing flavors, aromas, and textures. Food also provides our body with essential nutrients and non-nutrients like phytochemicals, both of which are vital to health. This section will discuss the six classes of nutrients and how these nutrients can be classified. Nutrients are chemical substances found in food that are required by the body to provide energy, give the body structure, and help regulate chemical processes. There are six classes of nutrients: 1. carbohydrates 2. lipids 3. proteins 4. water 5. vitamins 6. minerals Nutrients can be further classified as either macronutrients or micronutrients and either organic or inorganic, as well as whether or not they provide energy to the body ( energy-yielding). We’ll discuss these different ways of classifying nutrients in the following sections. Nutrients that are needed in large amounts are called macronutrients. There are three classes of macronutrients: carbohydrates, lipids, and proteins. Water is also a macronutrient in the sense that you require a large amount of it, but unlike the other macronutrients, it does not yield energy.se that you require a large amount of it, but unlike the other macronut Figure 1.5. Macronutrients include proteins, carbohydrates, lipids, and water. This figure illustrates each nutrient’s chemical structure and examples of food sources. Carbohydrates are molecules composed of carbon, hydrogen, and oxygen. The major food sources of carboh...

The carbohydrates are an important class of naturally occurring organic compounds These include glucose (grape sugar), fructose (Honey sugar), Sucrose (Cane sugar), Starch and cellulose (wood). They are all composed of C, H and O. In general, carbohydrates can be represented by the formulaC m(H 2O) n. • • • • • • What are Carbohydrates? The carbohydrates are polyfunctional compounds. They contain the following functional groups. • Alcoholic hydroxy groups, -OH • Aldehyde group -CHO • Ketone group, -CO- A precise definition of the term ‘Carbohydrate’ can be given as Polyhydroxyaldehydes or polyhydroxy ketones, and large molecules that produce these compounds on hydrolysis. This may be illustrated by citing the example of the two simplest carbohydrates containing three carbon atoms. Classification of Carbohydrates The carbohydrates is divided into three major classes depending on the number of simple sugar units present in their molecule. In other words, the basis of classification of carbohydrates will be the number of simple sugar molecules produced on hydrolysis. The molecules so obtained may be of the same or different sugars. • Monosaccharides • Oligosaccharides • Polysaccharides Types of Carbohydrate Common Foods Uses by Humans Monosaccharides Glucose, Galactose, Fructose Cereal grains and pasta, vegetables, fruits, and fruit juices, nuts and seeds Fructose is a sugar found in Fruits. All these are simple sugars which are easily digested by the body and a ready source ...

(CH 2 O)n is the general empirical structure of carbohydrates. Monosaccharides are simple sugars that serve as fuel molecules and fundamental constituents of living organisms and these are the simplest carbohydrates required as the energy sources. Glucose and fructose are the most commonly known carbohydrates. Structure of Carbohydrates Carbohydrates has historically been characterized as compounds with the n (H 2 O)m. Glucose, fructose, and sucrose are popular sugars that suit this formula, however, nowadays, a carbohydrate is defined as a polyhydroxy aldehyde or polyhydroxy ketone with the classical formula, a molecule closely similar to it, or oligomers or polymers of such molecules. Because they are water-soluble and difficult to crystallize, they require a different set of abilities to manage than traditional "natural products" like terpenes, steroids, and alkaloids. A "monosaccharide" is a carbohydrate derivative having a single carbon chain; "disaccharide" and "trisaccharide" are the compounds, which are made up of either two or three monosaccharide units linked either by acetal or ketal linkages. Larger aggregates with "a few" and "many" monosaccharide units are referred to as "oligosaccharide" and "polysaccharide," respectively. The divide between "few" and "many" appears to be established at around 10 units in current usage. By the middle of the nineteenth century, chemists in Europe, particularly in Germany, had discovered a variety of relatively pure carbohydra...