ESSENTIAL PROCESSES OF LIFE

To re-emphasise the central role of ATP generation in the biochemical and physiological functions in the body, a summary of the sequence of the biochemical pathways and processes by which the energy in food is used to generate the ATP that supports the essential processes of life is provided in Figure 9.30. 

Biocatalysis is a central research area at the interface of chemistry and biology. All essential processes of life are accelerated by enzymes, and the high efficiency and enormous selectivity of enzymes have fascinated generations of scientists. Understanding how metabolically relevant enzymes work has therefore been at the core of biochemical research for decades, and scientists have established an ever-growing toolbox to study and tailor biocatalysts. Numerous Nobel Prizes, both in chemistry and in physiology or medicine, have been awarded for groundbreaking studies on the roles, structures, or mechanisms of various enzymes. 

Each product system consists of a variable number of processes involved in the product life cycle. However, the product under consideration is often related to other processes that may no longer be important for the LCA study. The system boundary serves to the separation of essential and non-essential processes of the product life cycle. Since the choice of system boundaries significantly affects LCA study outcomes and in addition, its intensity and complexity, system boundaries should always be well considered and clearly defined. The choice of system boundaries is carried out with regard to the studied processes, studied environmental impacts and selected complexity of the study. Not-including any life cycle stages, processes or data must be logically reasoned and clearly explained [32]. 

Sections I-V of this chapter deal with the syntheses of unsaturated organic compounds playing an essential role in biochemical processes of life. Numerous polyunsaturated compounds have been synthesized in order to elucidate their physiological role, for instance in brain. However, the main impact on permanent searches for new improved methods of synthesis of isotopically labelled dienes and polyenes comes from nuclear medicine and nuclear pharmacy. The deuterium and carbon-13 labelled polyunsaturated compounds are needed as internal standards in mass spectral determinations of very low concentrations of biologically active substances in biological fluids. 

Chirality is an essential property of life, which can be found throughout all biological self-assembled and self-organized architectures. Over many millennia nature has, through trial and error, learned how to utilize the chiral properties of the small building blocks, for example, amino acids and nucleic acids and how to express this structural property in a hierarchical process at the quaternary level. This expression of chirality at the quaternary level in turn... 

Compounds with heterocyclic rings are inextricably woven into the most basic biochemical processes of life. If one were to choose a step in a biochemical pathway at random, there would be a very good chance that one of the reactants or products would be a heterocyclic compound. Even if this was not true, participation of heterocyclics in the reaction in question would almost be certain as all biochemical transformations are catalyzed by enzymes, and three of the twenty amino acids found in enzymes contain heterocyclic rings. Of these, the imidazole ring of histidine in particular would be likely to be involved histidine is present at the active sites of many enzymes and usually functions as a general acid-base or as a metal ion ligand. Furthermore, many enzymes function only in the presence of certain small non-amino acid molecules called coenzymes (or cofactors) which more often than not are heterocyclic compounds. But even if the enzyme in question contained none of these coenzymes or the three amino acids referred to above, an essential role would still be played by heterocycles as all enzymes are synthesized according to the code in DNA, which of course is defined by the sequence of the heterocyclic bases found in DNA. 

In photobiology these negative actions start with the processes which modify or destroy the essential molecules of life, specifically the nucleic acids and the proteins. The former carry the genetic code in a sequence of nucleotides and even a minor modification of the nucleotide sequence can have profound consequences. By the laws of chance alone these modifications and their consequences are almost always detrimental and result usually in the death of the organism (e.g. microbes) exposed to short-wavelength ultraviolet radiation. 

Potable water is hard to win because of the very properties that make it worth winning. Because of its unique properties, it exists as a liquid instead of a gas and as a liquid it penetrates into and interacts with living tissues to make possible the processes of life. Because it dissolves salts and nutrients, it is essential for the metabolism of all living cells. 

Today, about half of all the nitrogen consumed by all the world s crops each year comes not from natural sources such as bacteria in the soil, but from ammonia factories employing the Haber-Bosch process. It has become an essential pillar of life on earth, a fountain that feeds its growing population. According to the most careful estimates, some two billion people who live on our planet today, mainly in Asia, could not survive in the absence of Fritz Haber s invention. 

Assimilatory Processes Building the Essential Molecules of Life... 

Photochemistry is probably the most essential process for life as we know it. At the risk of gross impertinence, one of the first references to illumination is from the book of Genesis, "And God said Let there be light and there was light. And God saw the light, that it was good" [2]. 

In theory, bimolecular and trimolecular complexes could be generated by the self-assembly of the above first two or three types of molecules, showing the most essential attributes, or fundamental processes of life, but without requiring the existence of a discrete living cell in the prebiotic environment. The existence of a more complex living entity. 

Approximately one-third of all proteins in the human body contain metals. These and other metalloproteins are essential for the basic processes of life, including DNA synthesis, metabolism photosynthesis detoxification, and the chemical transformations of nitrogen, oxygen, and carbon molecules required for life. Many diseases are due to metal imbalances or inactivity of critical metalloproteins. In fact, numerous essential biological functions require metal atoms. Thus, metalloproteins make life on Earth possible and the ability to understand and ultimately control the binding and activity of protein metal sites is of great biological and medical importance. 

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