Living organisms diversity

In the Chapter 6 Focus On, "Terpenes Naturally Occurring Alkenes," we looked briefly at terpenoids, a vast and diverse group of lipids found in all living organisms. Despite their apparent structural differences, all terpenoids are related. All contain a multiple of five carbons and are derived biosynthetically from the five-carbon precursor isopentenyl diphosphate (Figure 27.6). Note that formally, a... 

The central theme of this introductory chapter has been the unity of hfe at the molecular level. Despite the diversity of size, shape, symmetry, habitat, or lifestyle, aU living organisms share a common set of molecules proteins and nucleic acids foremost among them. It follows that there are chemical connections between all things biological. 

Like living organisms themselves, cells come in a remarkable variety of flavors. Brown has described what might be a human cell with elaborate internal structure. However, there is no such a thing as a typical cell. Afunctional liver cell, a hepatocyte, is quite distinct from a nerve cell, a neuron, that, in turn, is not much like a cell of the retina of the eye. Skin cells, pancreatic cells, kidney cells, cells of the testis and ovary, red blood cells, bone cells, and on and on, are all structurally, functionally, and metabolically distinct. Indeed, there are several types of cells in the skin, pancreas, kidney, testis, ovary, and bone. Then there are the cells of bacteria and other microorganisms that have no nucleus or other membrane-limited organelles very different. Diversity abounds. 

The essentials of chemistry and physics are unchanging. They reflect the basic, static properties of matter. In contrast, life, and therefore biology, is constantly changing and evolving as different varieties of living organisms are created from the same fundamental elements. The diversity of life is a study of variations on a single chemical theme. 

While almost any living organism can be considered a potential source of useful enzymes, in practice a limited number of plant and animal tissues are economic sources and the greatest diversity comes from microorganisms and recombinant products. 

For survival purposes, all living organisms rely on an ability to transform and interconvert a diverse set of organic and inorganic compounds in order to utilize them as a source of energy and as their structural building... 

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