Plant compounds, carbohydrates

Carbohydrates are the most abundant organic component of plants. Structurally, carbohydrates are usually polyhydroxy aldehydes or polyhydroxy ketones (or compounds that hydrolyze to yield polyhydroxy aldehydes and ketones). Since carbohydrates contain carbonyl groups and hydroxyl groups, they exist primarily as acetals or hemiacetals. 

The processes generating plant compounds have been separated into primary and secondary metabolism. Primary metabolism produces the basic products for the life of the plant like carbohydrates, amino acids, fatty acids, polysaccharides, proteins, lipids, RNA and DNA. The primary metabolites are produced in relatively large quantities and their distribution is universal. On the contrary, the secondary metabolites are... 

The movement of most organic compounds throughout the plant takes place in the other vascular tissue, the phloem. A portion of the photosynthetic products made in the mesophyll cells of the leaf diffuses or is actively transported across cellular membranes until it reaches the conducting cells of the leaf phloem. By means of the phloem, the photosynthetic products— which then are often mainly in the form of sucrose—are distributed throughout the plant. The carbohydrates produced by photosynthesis and certain other substances generally move in the phloem toward regions of lower... 

Pinho E, Grootveld M, Soares G, Henriques M. Cyclodextrins as encapsulation agents for plant bioactive compounds. Carbohydr Polym. )an 30, 2014 101 121-135. 

An ever-increasing amount of carbon dioxide (CO2) is found in the atmosphere and the oceans, apparently as a result of continuing combustion of fossil fuels and normal life processes. Additionally, much of the biosphere contains carbon locked in plants (as carbohydrates [Chapter 11] and related materials about which you will learn). However, most of the compounds of carbon in use today in our technology are obtained either directly from coal or from petroleum—thought by many to have arisen by application of heat and pressure to the decaying products of earlier biosphere inhabitants or by laboratory modification of those materials. 

Carbohydrates are found in all living organisms. Indeed, they are the most abundant of the natural organic compounds. It is estimated that well over half the organic carbon on earth is in the form of carbohydrates, the great majority of it in plants. Almost three-fourths of the dry weight of plants is carbohydrate, most of which is in cell walls (structural components). In higher land plants, these carbohydrate components of the cell wall are cellulose, the hemicelluloses, and the pectic substances. The subject of this chapter is the carbohydrates other than those that are constituents of primary or secondary cell walls. 

As energy yielding compounds, carbohydrates together with proteins, fats, and a few minerals represent the sine qua non of a nutritionally essential diet. In the United States, most people are waking up to the fact that a diet rich in plant foods is healthy and protective. The modem nutritional wisdom of a diet rich in... 

Various aquatic plants, such as reed manna grass Glyceria maxima), rice-plant, Arundodonax and Anisogrammaanomala, have been used for PMFCs. Water-soluble root exudates of these plants, including carbohydrates, carboxylic acids and amino acids serve as the most important electron donors for electricity production. In addition, soil (if present) can also act as an electron source via chemical or anaerobic respiration processes, such as chemical oxidation of humic acids, iron(ll), and sulphur compounds, and microbial oxidation of sulphur and ammonia by specific microbes. 

The major classes of organic compounds common to living systems are lipids pro terns nucleic acids and carbohydrates Carbohydrates are very familiar to us— we call many of them sugars They make up a substantial portion of the food we eat and provide most of the energy that keeps the human engine running Carbohy drates are structural components of the walls of plant cells and the wood of trees Genetic information is stored and transferred by way of nucleic acids specialized derivatives of carbohydrates which we 11 examine m more detail m Chapter 28... 

Early investigators grouped alkaloids according to the plant families in which they are found, the stmctural types based on their carbon framework, or their principal heterocycHc nuclei. However, as it became clear that the alkaloids, as secondary metaboUtes (30—32), were derived from compounds of primary metabohsm (eg, amino acids or carbohydrates), biogenetic hypotheses evolved to link the more elaborate skeletons of alkaloids with their simpler proposed pregenitors (33). These hypotheses continue to serve as valuable organizational tools (7,34,35). 

Even higher organisms can be used for the production of labeled compounds. Plants, tobacco, or Canna indica for example, when grown in an exclusive atmosphere of radioactive carbon dioxide, [ 002], utilize the labeled precursor as the sole source of carbon for photosynthesis. After a suitable period of growth, almost every carbon atom in the plant is radioactive. Thus, plants can serve as an available source of C-labeled carbohydrates (9). 

Kacurakova, M., Capek, P., Sasinkova, V., WeUner, N. Ebringerova, A. (2000). FT-IR study of plant cell wall model compounds pectic polysaccharides and hemicelluloses. Carbohydrate Polymers, Vol. 43,2, (October 2000), pp. (195-203), ISSN 0144-8617... 

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