Living Machinery

His important works include Muscular Activity (1926) and Muscular Movement in Man (1927), as well as Living Machinery (1927), The Ethical Dilemma of Science and Other Writings (1960), and Traits and Trials in Physiology (1965). 

The balance of this chapter will be devoted to several classic and representative enzyme mechanisms. These particular cases are well understood, because the three-dimensional structures of the enzymes and the bound substrates are known at atomic resolution, and because great efforts have been devoted to kinetic and mechanistic studies. They are important because they represent reaction types that appear again and again in living systems, and because they demonstrate many of the catalytic principles cited above. Enzymes are the catalytic machines that sustain life, and what follows is an intimate look at the inner workings of the machinery. 

Viruses lack independent metabolism. They multiply only inside living cells, using the host cell metabolic machinery. Some virus particles do contain enzymes, however, that are under the genetic control of the virus genome. Such enzymes are only produced during the infection cycle. 

The axon comprises a major portion of the total volume and surface area in most neurons and may extend several thousand cell body diameters. Since the genetic material and nearly all the protein synthesis machinery are localized to the cell body, a supply line is maintained to provide structural and functional materials to sites all along the length of the axon. Insights as to how neurons accomplish this task can be obtained by real-time imaging of living axons with video-enhanced light microscopy [1] (Fig. 28-1). 

The relationship between the DNA in the nucleus and proteins in the cytoplasm is not direct. The information in the DNA molecule is transmitted to the protein-synthesizing machinery of the cell via another informational nucleic acid, called messenger RNA (mRNA), which is synthesized by an enzyme called RNA polymerase. Although similar to DNA, mRNAs are single-stranded, and possess the base uracil instead of thymine and the sugar ribose rather than deoxyribose. These molecules act as short-lived copies of the genes being expressed. 

The exchange of commodities between producers is underpinned by Marx s theory of value. In contrast to Adam Smith, a correct distinction is made by Marx between dead and living labour (see Chapter 2). Constant capital - raw materials, machinery and premises - are produced by past labour, in previous periods of production. Variable capital and surplus value are produced by living labour in the current period of production. For Luxemburg ... 

The Protos warfare on their Lept neighbors depended heavily on chemicals, but ants are by no means unique in making extensive use of chemicals for communication and warfare. From one-celled organisms to complex plants and animals, many living creatures do the same. As species develop over evolutionary time, it is relatively easy for them to adapt their cellular machinery to producing chemicals for communication, warfare, and other purposes. These chemicals facilitate the way of life of organisms spread all across the biological spectrum. 

More than most of us can hope for, Williams life was also filled with extraordinary gifts and accomplishments. For over 20 years he and his co-workers worked to discover, isolate, characterize and synthesize the substance he named pantothenic acid, an essential cog in the biochemical machinery of all living things. He also first concentrated and named folic acid, another B vitamin. As founder and director of the Clayton Foundation Biochemical Institute at the University of Texas at Austin from 1940 to 1963, he and his colleagues made many other notable contributions to nutrition and biochemistry. 

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