Читать книгу Biochemistry For Dummies - John Moore T., Richard Langley H., John T. Moore - Страница 31

Long ago, scientists believed that all carbon compounds were the result of biological processes, which meant that organic chemistry was synonymous with biochemistry under what was known as the Vital Force theory. In the mid-1800s, though, researchers such as Friedrich Wöhler debunked that long-held notion; the synthesis of urea, CO(NH₂)₂, from an inorganic material (ammonium cyanate, NH₄OCN) showed that other paths to the production of carbon compounds existed. Organic chemists now synthesize many important organic chemicals without the use of living organisms; however, biosynthesis is still an important source of many organic compounds.

Why are there so many carbon compounds? The answer lies primarily in two reasons, both tied to carbon’s versatility in creating stable bonds:

 Carbon bonds to itself. Carbon atoms are capable of forming stable bonds to other carbon atoms. The process of one type of atom bonding to identical atoms is catenation. Many other elements can catenate, but carbon is the most efficient at it. There appears to be no limit to how many carbon atoms can link together. These linkages may be in chains, branched chains, or rings, as shown in Figure 3-1.

 Carbon bonds to other elements. Carbon is capable of forming stable bonds to a number of other elements. These include the biochemically important elements hydrogen, nitrogen, oxygen, and sulfur. The latter three elements form the foundation of most of the functional groups (reactive groups of a molecule) necessary for life. Bonds between carbon and hydrogen are usually unreactive under biochemical conditions; thus, hydrogen often serves as an inert substituent (an atom or group of atoms taking the place of another atom or group or occupying a specified position in a molecule).

FIGURE 3-1: Top: straight chain hydrocarbon expanded and condensed. Middle: branched chain hydrocarbon. Bottom: ring hydrocarbon.