[...]... human health Living organisms create an amazingly diverse collection of molecules This valuable resource has yet to be fully exploited for good purposes and merits protection Living nature is divided into three great domains The three great domains of life on Earth are the Archaea, the domain of archaeans, the Eubacteria, the domain of bacteria, and the Eukarya, the domain of eukaryotes The Archaea and. .. complement of Eubacteria and Archaea are distinct: about 30% of all Archaea genes are unique to archaeans Finally, the lipids that constitute the cell membrane are distinct There are clear and compelling distinctions between these two great domains of life Eukaryotes are differentiated from the Archaea and Eubacteria by the possession of a nucleus in the cell enclosed by a membrane as well as by membrane-enclosed... Diversity abounds At the same time, all cells are unified at the molecular level, as emphasized in the first chapter There are other commonalities as well.All cells have a plasma membrane that surrounds and encloses them The fundamental function of the plasma membrane is to act as a selective barrier between the cell interior and the external environment In the Eubacteria and Archaea, single cell organisms all,... diversity of habitat The cold Arctic seas swarm with marine microorganisms The ice floes suspended in these seas are home to sea lions, seals, and polar bears At the other end of the world, penguins huddle together on the landmass of frigid Antarctica, 95% of which is covered by a massive ice cap that averages 1.6 kilometers, about 1 mile, thick At the other end of the temperature scale are the habitats of the. .. metabolic and signaling pathways of the cell.3 This has been a focal point of biochemistry for many years and a lot of relevant information is available We do not have a complete picture but we do have a reasonable grip on this issue 20 THE TAO OF CHEMISTRY AND LIFE Beyond having the metabolic pathways, we need to understand the control circuits that regulate them Of particular interest is the control of the. .. something? The building of knowledge usually begins with an observation or an idea leading to a hypothesis: a tentative statement of belief To be any good, a hypothesis must fulfill certain criteria: it must be testable, 6 THE TAO OF CHEMISTRY AND LIFE falsifiable, and have predictive value Here are some examples of hypotheses that meet these criteria, though not all of them are true: the Earth moves about the. .. 900,000 years or 450 times as long as the time between the birth of Christ and the present day Bacteria are really small UNITY OUT OF DIVERSITY 7 At the other end of the scale are the giant sequoias that tower 200 feet, about 65 meters, above the ground and weigh thousands of tons A single leaf from such a tree weighs as much as millions of tiny bacteria Put another way, it would take several hundred... cellular structures that had a lower mutation rate and a much slower rate of lateral genetic transfer among cells This was followed by evolution of cellular subsystems, adding a new level of cellular complexity From these cells came the three great domains of living organisms: the Eubacteria, Archaea, and Eukarya The origin of living organisms on Earth has been summed up by Carl Woese, one of the leaders... species of birds are discovered each year The fact is that we do not understand the range of living organisms that cohabit the Earth with us well at all We are far nearer the beginning than the end of that understanding E O Wilson has beautifully described the range of life on Earth in his book: The Diversity of Life. 5 An international effort has been organized to summarize all knowledge of the 1.8 million... reign of dinosaurs on Earth and which has captured the public imagination in a way that no other can This is the extinction at the Cretaceous–Tertiary boundary, 65 million years ago.8 Perhaps the most likely explanation for this extinction is the impact of a large meteorite on the surface of the Earth This theory suggests that the collision kicked up a tremendous amount of dust that blanketed the planet, . observation, experimentation, and rigorous testing The worldworks based ona set of mutually agreedunderstandings. Theseunderstand- ings take many forms: mathematical equations; the laws of physics and chemistry; and. testable, 6 THE TAO OF CHEMISTRY AND LIFE falsifiable, and have predictive value. Here are some examples of hypotheses that meet these criteria, though not all of them are true: the Earth moves about. include a genus of bacteria termed Mycoplasma and some members of a great domain of living organisms, the Archaea. These organisms measure only about a thousandth of a millimeter 2 long in their biggest