The Structure of Living Organisms

Chemical investigation of the plant viruses has shown that they consist of the materials called proteins and nucleic acids, the nature of which is discussed in this chapter and the following chapter. The giant virus particles or molecules, with molecular mass of the order of magnitude of 10,000,000, may be described as aggregates of smaller molecules, tied together in a definite way. 

---

Morphological Relating to the configuration or the structure of live organs. [NIH]... 

Amino Acids and Proteins. Proteins are the molecules that perform the functions of life. They can be enzymes that catalyze biological reactions, or they can be the receptor site on a membrane that binds a specific substance. Proteins are important parts of both bones—the so-called hard biologies—and the soft biologies such as muscle and skin. Any discussion of the structure of living organisms must begin with the structure of proteins. 

Look for a moment at the periodic table inside the front cover of this book. More than a hundred elements are hsted there. The question that comes to mind is this why should an entire field of chemistry be based on the chemistry of compounds that contain this one element, carbon There are several reasons, the primary one being this carhon compounds are central to the structure of living organisms and therefore to the existence of life on Earth. exist because of carbon compounds. 

The control of these parameters allowing for the development of highly complicated structures of living organisms which are able to reproduce, to pass on genetic information to the next generations, and to carry out various specialized functions. 

Nucleic acids are of great interest because they are the units of heredity, the genes, and because they control the manufacture of proteins and the functions of the cells of living organisms. Hydrogen bonds play an important part in the novel structure proposed for deoxyribonucleic acid by Watson and Crick.1,5 This structure involves a detailed eomplement riness of two intertwined polynucleotide chains, which form a double helix.117 The complementariness in structure of the two chains was attributed by Watson and Crick to the formation of hydrogen bonds between a pyrimidine residue in one chain and a purine residue in the other, for each pair of nucleotides in the chains. 

The stereospecificity of living organisms is imperative to their efficiency. The reason is that it is just not possible for an organism to be so constructed as to be able to deal with all of the theoretically possible isomers of molecules with many asymmetric centers. Thus a protein molecule not uncommonly has 100 or more different asymmetric centers such a molecule would have 2100 or 1030 possible optical isomers. A vessel with a capacity on the order of 107 liters would be required to hold all of the possible stereoisomeric molecules of this structure if no two were identical. An organism so constituted as to be able to deal specifically with each one of these isomers would be very large indeed. 

Molecular and supramolecular morphogenesis is at its highest expression in the generation of biological structure in the course of the development of living organisms [7.63]. 

The essential structures of living organisms range in scale from molecular to micron dimensions. An important objective in supramolecular research is to... 

Various organisms were selected to address the effects of diterpenes on different organizational structures and sensitivities. Alternative, small-scale aquatic toxicity tests known as microbiotests were used. These tests are independent of the culturing of live organisms and based on immobilized or dormant (cryptobiotic) stages of aquatic species set free or hatched when needed. The following bioassays for freshwater supplied by Creasel, Deinze, Belgium were applied ... 

We see, then, that for the organism not only does identity persist in material change but it depends on this material flux. This is what is meant by the statement that its selfhood is derived from its experience of itself as a process. Its self-awareness does not apply to a material structure, but to an event-structure. The event-structure, the process in question, is the persistence and development of bodily form in the face of material flux. For in the case of living organisms, form is not determined by material substrate ... 

---