Organism, living

The C exchanges with C in living organisms, but exchange ceases on death. The radioactive content decays with a half-life of 5730 years. Hence the age of a once living material may be established by determining the amount of C. 

Phosphorus compounds are very important as fertilizers (world use 1976/77 27-3 megatonnes as P2O5) but are widely used in matches, pesticides, special glasses and china ware, alloys (sleels. phosphor bronze), and metal treating (10%), detergents (40%), electrical components (e.g. GaP), foods and drinks (15%). Phosphates are an essential constituent of living organisms. U.S. production of phosphorus 1982 372 000 tonnes. 

Biological reactions in vivo rarely operate under conditions even remotely approaching those of reversibility. For a living organism, the rate of a process is usually more important than the attainment of equilibrium, and large driving... 

The ability of living organisms to differentiate between the chemically similar sodium and potassium ions must depend upon some difference between these two ions in aqueous solution. Essentially, this difference is one of size of the hydrated ions, which in turn means a difference in the force of electrostatic (coulombic) attraction between the hydrated cation and a negatively-charged site in the cell membrane thus a site may be able to accept the smaller ion Na (aq) and reject the larger K (aq). This same mechanism of selectivity operates in other ion-selection processes, notably in ion-exchange resins. 

Calcium plays an important part in structure-building in living organisms, perhaps mainly because of its ability to link together phosphate-containing materials. Calcium ions in the cell play a vital part in muscle contraction. 

Once a reaction has been performed, we have to establish whether the reaction took the desired course, and whether we obtained the desired structure. For our knowledge of chemical reactions is stiU too cursory there are so many factors influencing the course of a chemical reaction that we are not always able to predict which products will be obtained, whether we also shall obtain side reactions, or whether the reaction will take a completely different course than expected. Thus we have to establish the structure of the reaction product (Figure 1-4). A similar problem arises when the degradation of a xenobiotic in the environment, or in a living organism, has to be established. 

Porphyrins and chlorophylls are the most widespread natural pigments. They are associated with the energy-converting processes of respiration and photosynthesis in living organisms, and the synthesis of specific porphyrin derivatives is often motivated by the desire to perform similar processes in the test tube. The structurally and biosynthetically related corrins (e.g. vitamin B,j) catalyze alkylations and rearrangements of carbon skeletons via organocobalt intermediates. The biosyntheses of these chromophores are also of topical interest. 

Recall that free energy is the energy available to do work By focusing on free energy we concern ourselves more directly with what is impor tant to a living organism... 

Chromosomes are extremely complex chemicals that are assembled from simple repeating units and contain all the chemical information needed to reproduce animate species. Each living organism has its own complete set of chromosomes, called the genome. 

Biomass. Biomass is simply defined for these purposes as any organic waste material, such as agricultural residues, animal manure, forestry residues, municipal waste, and sewage, which originated from a living organism (70—74). 

Lactic acid [50-21-5] (2-hydroxypropanoic acid), CH CHOHCOOH, is the most widely occurring hydroxycarboxylic acid and thus is the principal topic of this article. It was first discovered ia 1780 by the Swedish chemist Scheele. Lactic acid is a naturally occurring organic acid that can be produced by fermentation or chemical synthesis. It is present ia many foods both naturally or as a product of in situ microbial fermentation, as ia sauerkraut, yogurt, buttermilk, sourdough breads, and many other fermented foods. Lactic acid is also a principal metaboHc iatermediate ia most living organisms, from anaerobic prokaryotes to humans. 

Vimses are obligate intracellular parasites. They only exhibit activity by infecting other living organisms, thus they are not a practical concern in industrial microbiological fields. The exception is where viral contamination of the product or process represents a threat of transmission of disease. Microscopic insects and protozoans are also not addressed in this article (see Insectcontroltechnology). 

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