Carbohydrates from photosynthesis

The dependence of the amount of starch in woody tissues of various trees on season (see, for example, 72, 110), sunlight (see, for example, 122), foliation (see, for example, 178), nutrients (see, for example, 122), and the demand for monoterpene biosynthesis to repel insect attack (178) has been investigated as expected, the starch content is directly proportional to the availability of translocatable carbohydrates from photosynthesis and inversely proportional to energy demands for anabolic processes. 

Chlorophyll is present in all green plants, and is essential to the life of the plant, as it acts as a catalyst in the photosynthesis of carbohydrates from carbon dioxide and water. 

Chloroplasts are the site of photosynthesis, the reactions by which light energy is converted to metabolically useful chemical energy in the form of ATP. These reactions occur on the thylakoid membranes. The formation of carbohydrate from CO9 takes place in the stroma. Oxygen is evolved during photosynthesis. Chloroplasts are the primary source of energy in the light. 

As we began this chapter, we saw that photosynthesis traditionally is equated with the process of COg fixation, that is, the net synthesis of carbohydrate from COg. Indeed, the capacity to perform net accumulation of carbohydrate from COg distinguishes the phototrophic (and autotrophic) organisms from het-erotrophs. Although animals possess enzymes capable of linking COg to organic acceptors, they cannot achieve a net accumulation of organic material by these reactions. For example, fatty acid biosynthesis is primed by covalent attachment of COg to acetyl-CoA to form malonyl-CoA (Chapter 25). Nevertheless, this fixed COg is liberated in the very next reaction, so no net COg incorporation occurs. 

Plants synthesize carbohydrates from C02 and H20 by the process of photosynthesis. For example,... 

Photosynthesis occurs only in plants, algae, and some bacteria, but all forms of life are dependent on its products. In photosynthesis, electromagnetic energy from the sun is used as the driving force for a thermodynamically unfavorable chemical reaction, the synthesis of carbohydrates from C02 and H20 (Equation E9.1). 

Of particular importance is the conversion of much of the energy that results from photosynthesis, or from the oxidation of fats, carbohydrates, and proteins in cells into formation of phosphate ester bonds (C—O—P) or phosphate anhydride bonds (P—O—P). The energy so stored is used in other reactions, the net result of which is hydrolysis ... 

Photosynthesis. The biosynthesis that directly harnesses the chemical energy resulting from the absorption of light. Frequently used to refer to the formation of carbohydrates from CO2 that occurs in the chloroplasts of plants or the plastids of photosynthetic microorganisms. 

A cartoon of the carbon cycle is given in Figure 15.6 [8]. A key reaction from photosynthesis uses the energy of the sun to convert C02 and water into oxygen and carbohydrate... 

Photosynthesis uses solar energy to synthesize carbohydrate from carbon dioxide and water. In the light reactions, the light energy drives the synthesis of NADPH and ATP. In the dark reactions (carbon-fixation reactions), the NADPH and ATP are used to synthesize carbohydrate from C02 and H20. 

Photosynthesis occurs in green plants, algae and photosynthetic bacteria. Its role is to trap solar energy and use this to drive the synthesis of carbohydrate from carbon dioxide and water. Using (CH20) to represent carbohydrate, the overall reaction is ... 

In contrast to plant cells, which normally get their cellular energy from photosynthesis, animal cells need a carbohydrate source, usually glucose, and the amino acid glutamine. The catabolism of these substrates allows the production of two coenzymes (ATP and NADH - nicotinamide adenine dinucleotide), which are essential for maintaining the viability of the cells. These coenzymes can be used for the maintenance, metabolism and/or for the synthesis of particular desired products (Wagner, 1997). 

Photosynthesis process by which plants use light energy to make simple carbohydrates from carbon dioxide and water. 

Chemical reactions involving oxidation and reduction processes (redox reactions) are central to metabolism. The energy derived from the oxidation of carbohydrates is coupled to the synthesis of ATP via a series of redox reactions, the mitochondrial electron-transport chain (see Chap. 14). Moreover, most life on earth is dependent on a series of redox reactions in photosynthesis, the process in which solar energy is used to produce ATP and O2 and to synthesize carbohydrates from CO2. 

The reduction of CO2 to glucose (C6Hi20g) stores some of the Sun s energy in the chemical bonds of the organic matter formed. Glucose, cellulose, carbohydrates, protein, and fats are all forms of organic matter, or reduced carbon. They all embody energy and are nearly all derived ultimately from photosynthesis. 

Biosynthesis of carbohydrates from carbon dioxide occurs in the stroma region of the chloroplasts via the Calvin cycle. The formation of a six-carbon sugar molecule requires six complete turns of the Calvin cycle, for each of which three ATP and two NADPH molecules are consumed. The overall biochemistry of photosynthesis for the formation of one glucose molecule from six CO2 molecules may be written as ... 

Calvin-Benson cycle The synthesis of carbohydrate from C02, in particular during oxygenic photosynthesis... 

Photosynthesis is a process by which plants use light energy to manufacture carbohydrates from carbon dioxide and water. Because such substances are the primary source of energy for aU organisms, the results of photosynthesis provide energy for life on Earth. 

In Chapters 9 and 13, other related pathways are discussed. Photosynthesis, a process in which light energy is captured to drive carbohydrate synthesis, is described in Chapter 13. In Chapter 9 the glyoxylate cycle is considered. In the glyoxylate cycle some organisms (primarily plants) manufacture carbohydrate from fatty acids. 

Photosynthesis The process by which green plants, algae, and some kinds of bacteria produce carbohydrates from carbon dioxide and water. Chlorophyll captures and stores energy for the process. Oxygen is released as a byproduct of the process. 

In the use of radioactive tracers it is assumed that the radioactive isotopes studied are identical in chemical behavior to the nonradioactive isotopes. The first experiments that used radioactive tracers were carried out in 1913 in Germany and were designed to measure the solubility of lead salts via the use of a radioactive isotope of lead. In industry, radionuclides have been used for analytical purposes, for measurements of flow in pipes, and as part of many other apphcations. Another example of an important tracer study has been the investigation of photosynthesis of carbohydrates from atmospheric CO2 in the presence of light and chlorophyll. Scientists used eC, 15P, and iH to identify the intermediate steps involved in the photosynthesis of carbohydrates in plants that had been placed in an atmosphere composed of fyC-labeled CO2 and had been irradiated with hght. The presence of the radioactive carbon in the synthesized carbohydrate was evidence that O2 was involved in the synthesis. 

In the dark reactions of photosynthesis, NADPH and ATP produced by the light reactions are used in the reductive synthesis of carbohydrate from C02 and water. 

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