by Werner Gitt
Conclusion: It has not yet been possible to explain the incredible complexity of the molecular mechanisms on which photosynthesis is based. The same situation holds for respiration. The fact that the chemical equations and some of the intermediate enzyme driven steps are known should not create the impression that these processes are really understood; on the contrary, what we don’t yet know is incomparably more than what we do know. The American biophysicist Albert L. Lehniger [L1] regards these unresolved questions as some of the most fascinating biological problems. All solar energy engineers dream of devising a process which can convert sunlight directly into fuel. Although photosynthesis takes place in every single green leaf of all plants, having been conceived in an astoundingly brilliant way, even the most inventive engineer is unable to imitate the process. Every phototropic cell is supplied with the information required to undertake such an optimal energy conversion process.
A3.3 The Consumption of Energy in Biological Systems: Strategies for Minimization
Every cell requires energy continuously for its vital functions like the synthesis of new molecules, or the production of a daughter cell. In multicellular organisms there are further purposeful reactions (e.g., locomotion, and the control of body temperature). The conversion of energy in every cell, whether animal, vegetable, or microbial, is based on the same principles and mechanisms. In contrast to technological practices, living organisms avoid the inefficient use of heat as an intermediate energy form. Cellular processes are isothermic; this means that the temperature does not change.
The concept of energy: It should be emphasized that the energy-carrying nutrient molecules do not generate heat when they are oxidized. The molecular concept of biological oxidation involves numerous precisely tuned individual catalytic enzyme reactions which follow one another in exactly the required sequence, and employ just as many intermediate compounds. Adenosin triphosphate (ATP) has some special chemical properties which enable it to perform important functions. It belongs to the group of nucleotides, comprising adenine, C5-sugar, D-ribose, and phosphate groups. When nutrients are oxidized to generate energy, the more energy-rich ATP is formed from adenosin diphosphate (ADP). The energy stored in ATP can then subsequently be utilized by conversion into chemical work (e.g., biosynthesis), mechanical actions (e.g., muscular effort), or osmotic transportation. When this happens, the ATP loses one phosphate group, and reverts to ADP. In this energy transfer system, ATP is thus the charged substance, and the ADP is neutral. The numerous very complex intermediate chemical steps in this ATP/ADP energy cycle are catalyzed by a specific set of enzymes. In addition to this general flow of biological energy, there are some very clever special mechanisms for energy conversion.
Certain fishes like the electric eel can generate electrical pulses of several hundred volts directly from chemical energy. Similarly, light flashes emitted by some animals and organisms represent converted chemical energy. The bombardier beetle converts the chemical energy contained in hydrogen peroxide into explosive pressure and volume changes.
Machines constructed for the purpose of energy utilization essentially involve the generation of easily transportable electrical energy in a round-about way by first producing heat. Heat Q can only perform useful work W when there is a temperature difference T2-T1. The theoretical maximum amount of work that can be performed by a heat engine, is given by the Carnot formula:
W = Q x (T2-T1)/T2
T2 can be the initial temperature of the steam entering a turbine, for example, and T1 can be the exhaust temperature. It follows that large temperature differences are required to produce a reasonable amount of useful work. In living cells, the processes for generating energy must be fundamentally different, since all reactions have to take place at the temperature of the cell; in other words, the processes must be isothermic. The refined energy concepts realized in cells utilize substances which are unstable to heating, but still achieve exceptionally high degrees of efficiency.
The cells: A living cell can be compared with a factory comprising several departments, each of which has a certain number of machines.
The work of all the cell’s departments and machines involves optimally geared interrelationships exhibiting planning down to the last detail. The end products are produced through a coordinated sequence of numerous individual processes. We can rightly state that we are dealing with the smallest fully automated production line in the world; it even has its own computer center and its own power generating plants (the mitochondria). With their diameter of 100 nm, the prokaryotes are the smallest cells, while birds’ eggs are the largest. Ostrich eggs measure about 0.1 m = 108 nm, and the average radius of the cells of multicellular organisms lies between 2,000 nm and 20,000 nm (= 2 to 20 µm). Large living beings consist of tremendously large numbers of cells (about 1014 for humans), while the smallest organisms like bacteria are unicellular. Two large classes of cells are distinguished according to their structural organization, namely prokaryotic cells (Greek karyon = nucleus) and eukaryotic cells (Greek eu = good). Many unicellular organisms like yeast cells, protozoa, and some algae, are eukaryotic, as well as nearly all multicellular forms. Their cells contain a nucleus, mitochondria, and an endoplasmic reticulum. The prokaryotes comprise the bacteria and the blue algae. Compared to the eukaryotes, they are considerably smaller (only 1/5,000th in volume), less differentiated and less specialized, and they lack many of the structures like a nucleus or mitochondria.
Summary: We can now summarize the essential characteristics of energy utilization by organisms, which is fundamentally different from technological processes:
1. Isothermic energy conversion: Energy processes take place at a constant temperature (they are isothermic); pressures and volumes are also constant. The roundabout and inefficient technological methods which depend on the generation of heat are circumvented.
2. The greatest possible miniaturization: One of the aims of technology, the miniaturization of equipment, is realized in cells in a way that cannot be imitated. The energy generating and consuming processes in an organism are coupled at the molecular level. We can rightly speak of "molecular machines," representing the ultimate in miniaturization.
3. Optimal operation: Each and every one of the approximately ten thousand milliard (1013) muscular cells in the human body possesses its own decentralized "power generating plant." These can become operational as and when required, and are extremely economical as far as the transfer of energy is concerned.
4. The indirect conversion of energy: Energy is not applied directly, but the ATP system acts as a transfer medium from the energy-generating process to the reaction consuming energy. It should be noted that ATP, a substance of high energy content, is not used for storing energy, only to transfer it. The ATP-driven, energy-consuming processes can be of a very diverse nature: mechanical work is performed in contracting muscles; electrical energy is set free in the respective organs of some animals; when substances are absorbed or transported osmotic work is done, and in many cases the result is chemical work. All of these processes are included in an extensive metabolic chain effected by an extremely complex and often incompletely understood enzyme system.
5. High efficiency: Compared to fermentation (from glucose to lactic acid), respiration (from glucose to CO2 and H2O) is an extremely efficient process, releasing all the energy stored in glucose molecules. The efficiency of the transportation of electrons in this case is 91%, a ratio which engineers can only dream of. This fascinating process occurs in a brilliantly constructed system which continuously employs the "principle of a common intermediate product for the transfer of energy." ATP is the link between reactions which supply energy and those which require energy; in other words, cells have an energy exchange unit which is readily convertible. The processes which release energy provide the "currency" which is then spent by those processes requiring energy. The ATP system channels the transfer of energy, providing the cell with excellent control over the flow of energy.
T
he biological energy conversion system is so brilliantly and cleverly designed that energy engineers can only watch, fascinated. Nobody has yet been able to copy this highly miniaturized and extremely efficient mechanism.
A3.4 Conservation of Energy in Biological Systems
In regard to the relationship between physics and biology, Alfred Gierer, a physicist of Tübingen (Germany), concluded [G1]: "Physics is the most general science since it can be applied to all events in space and time, while biology is the most complex science which involves ourselves to a large extent." Some important questions now arise: Are there any processes occurring in living organisms where physical and chemical laws do not apply? Does a living organism differ fundamentally from a machine or not? Could biology be based on physics? Two aspects should be considered very carefully before we can answer such questions, namely:
1. Course of events: All biological processes strictly obey physical and chemical laws (see Theorems N2, N3, and N4 in paragraph 2.3). These laws, however, only delineate the external framework within which the relevant events generally occur. The environment imposes additional constraints. Furthermore, the inherent operational information (see chapter 11 for a definition) underlies all functions of living organisms. All these mostly very complex processes are program controlled.
2. Origin: Just as each and every machine, from a simple corkscrew to a computer, cannot be explained in terms of natural laws and environmental conditions only, so also does every biological system require an inventor, a constructor, a source of ideas. Every creator of a technological invention must know the laws of physics; he employs these laws to construct a suitable mechanism. Although the laws impose constraints, they also provide conditions which can be utilized. He displays his ingenuity when, by using constructional and architectural ideas, he constructs a machine which employs the natural laws in such a way that it is obviously an optimal solution. The same holds for the Creator of biological systems. How much more is His wealth of ideas and His unfathomable wisdom reflected in living systems!
Physical laws can describe and delineate the progress of biological processes, but they fail to explain their complexity and the wealth of their structures and functions. Anybody who discusses questions of origin and of spirituality on a purely material plane removes himself completely from the realities of life by such a mechanistic reduction.
The following examples of energy conservation illustrate the immeasurable inventiveness of the Creator. In many cases, the laws of nature are employed right up to the limits of what is physically possible.
A3.4.1 Animal "Chlorophyll"
Photosynthesis has now been recognized as a brilliant invention for the conversion of the energy of the sun to produce energy donors. There are three kinds of animal [D4] which have a similar "built-in" capacity, namely the snail Tridachia crispata, the three-millimeter spiral worm Convoluta roscoffensis which lives on the coast of Normandy and Bretagne, and the microscopic green Paramecium bursaria.
The tridachia snails are found in the waters around Jamaica and they normally subsist on seaweed, but when seaweed is not available, they can still survive. Chlorophyll eaten previously is not fully digested, but some of it is stored in the form of undamaged chloroplasts in leaf-shaped tufts on its back. These floral organelles are still functionally active and produce sugar when exposed to sunlight. This sugar is then distributed through its body to provide energy. It can now be stated that:
–The animal borrows the chemical factory of the plant, including its control information, and thus virtually changes itself into a plant.
– This snail ingests seaweed which then ensures sufficient nutrition for up to six weeks when exposed to sunlight. This is an amazing principle.
All human nutritional problems could be solved if only we could imitate these animals. Photosynthesis is such a brilliant information-controlled process that it is not really understood; it is also impossible to copy it chemotechnically. It has not yet been possible to imitate the above mentioned animals by utilizing and preserving chloroplasts (the chlorophyll organelles) with their functions intact, outside of leaf cells.
A3.4.2 Animals with "Lamps"
As far as energy is concerned, there is another extremely interesting phenomenon exhibited by many sea animals and some simple land animals (e.g., glowworms; see details in [G15]), namely bioluminescence (Latin lumen = light). These organisms can emit light of various colors (red, yellow, green, blue, or violet) and in different signal sequences. When technological light production is compared to bioluminescence, the former proves to be extremely inefficient as far as energy input is concerned. Normally, an electric light bulb only converts 3 to 4 percent of the applied energy into light, and the efficiency of a fluorescent tube is only about 10%. Our lamps could be considered to be heat generators rather than radiators of light.
Bioluminescence, being an invention of the Creator, involves the radiation of cold light — a reaction which no man has yet been able to copy. In this process, certain illuminative substances (luciferin) are oxidized by an enzyme called luciferase. Three fundamentally different types of luciferin can be distinguished, namely that of bacteria, that of fireflies, and that of the Cypridina. An American biochemist, professor W.D. McElroy, was able to quantify the efficiency of this type of light production. It was found that each and every quantum of energy transported to the light organ in the form of ATP[28] was converted to light. The number of oxidized luciferin molecules is exactly equal to the number of emitted light quanta. All the light emitted by a firefly is "cold" light, which means that there is no loss of energy through the radiation of heat. We are thus dealing with lamps which are 100% efficient because of the complete conversion of energy into light.
Many bacteria, tiny organisms, insects, and deep sea fishes especially, have been equipped with this method of producing light by the Creator. The best-known examples are the fireflies and the glowworms (Lampyris and Phausis). Most of the subtropical and tropical lampyrids can emit deliberate sequences of flashes; the European ones are not able to do this. In experiments with the black firefly (Photinus pyralis) it was found that the flying male emitted 0.06 second flashes at intervals of 5.7 seconds, and the female on the ground replied after exactly 2.1 seconds with the same rhythm.
These flashing signals are obviously understood by the prospective mate. There also are insects that have lamps which emit different colors, like the Brazilian train worm (Phrixothrix). This beetle larva (Driliden) which lives on snails, normally carries two orange-red lights in front. At the approach of danger, two sets of 11 greenish lanterns are switched on, one on each side. This resembles a train, and the name "train worm" is quite apt.
During a visit to Israel in 1985, we went to the underwater observatory in Eilath and could watch the lantern fish (Photoblepharon palpebratus steinitzi) living in the Red Sea. This fish does not produce its own light, but obtains it from symbiotic luminescent bacteria. These bacteria are so small that the light of a single one is invisible, but the light of an entire colony can be observed. They congregate on an oval light organ situated below the eyes of the fish and are fed and provided with oxygen through a densely branching network of capillary blood vessels. They continuously generate light, but the fish can deliberately switch the light on and off. It does this by pulling a black skin flap over the luminescent organ like an eyelid, and is thus able to transmit different flashing signals. These signals attract the prey it requires for subsistence.
Bacterial emission of light is fundamentally different from that of other luminescent organisms. Other marine organisms only emit light when they are disturbed or stimulated (e.g., by the passage of a ship or of a mackerel school, or the breaking of waves), but bacteria continuously emit light of a constant intensity.
The bioluminescence of abyssal creatures, like glowing fishes, crabs, arrow worms, and jellyfishes, is quite impressive. Many kinds of fish have lamps along their sides, while others have several rows of lamps. The luminous organs can be arr
anged in curves, in oscillatory patterns, or quite irregularly. The five-striped star constellation fish (Bathysidus pentagrammus) has five beautiful shining lines on both sides of its body, each of which consists of a row of large pale yellow lights, surrounded by serrated bright purple "jewels."
Luminous shrimps (Sergestes prehensilis) have more than 150 light points, all of which can be quickly switched on and off. For one or two seconds yellow-green lights flash sequentially and quickly from head to tail, just like neon advertisements in cities. Many kinds of fish employ luminescent bacteria to generate light flashes, but others have highly specialized organs which produce their own luminous substances. Some fishes have intricately constructed light projectors, concentrating lenses, or other optical equipment which can, for example, direct a ray of light in a specific direction. The projectors are constructed in such a way that a mosaic of thousands of minute crystals acts as a perfect mirror behind the luminous tissues. Some creatures even have color filters (pigment membranes) for producing any shade of color.
The inventiveness of the Creator is infinite, and we can only stand amazed.
A3.4.3 The Lung, an Optimal Structure