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As Mr. Tappin rose from behind the defense table, he grabbed the material being handed to him. He started to walk toward Dr. Yardley, stopped and retraced his steps.

He leaned over and whispered something in the ear of his colleague. When he received an affirmative response, he straightened up.

On his way back to the area near the witness stand, he was busy inspecting the new batch of material. He continued to do so for a further ten or fifteen seconds after stopping in front of the witness stand.

Finally, he said: "In your direct examination testimony you referred to an experiment by Fox in which urea [CO (NH₂)₂] and malic acid (C₄H₆O₅) were heated to 150 degrees Celsius under conditions free from water - that is, which were anhydrous in nature. You indicated this experiment resulted in the synthesis of aspartic acid.

"In a further experiment, also performed by Fox, you talked about a recipe for generating polymers or bonded chains of amino acid. In this recipe, if one cooked the amino acid glutamic acid in an oil bath for one hour at 170 degrees Celsius, and then blended in a variety of other amino acids and cooked the whole mixture for a further three hours at the same 170 degrees Celsius, then one could produce a chain of amino acids consisting of up to a hundred units.

"In variations on this experiment, phosphoric acid was added, and the variables of time and temperature were played around with during different runs of the same experiment. This resulted in an increase in the amounts of neutral and basic amino acids which could be incorporated into the polymer chain of amino acids.

"You also described another experiment in which sunlight was passed through a solution of paraformaldehyde (CH₂O)₃, ammonia and ferric chloride. After a certain amount of time, this arrangement brought about the synthesis of the amino acids serine and asparagine.

"During direct examination testimony, you talked, as well, about an experiment by Oro in which hydrogen cyanide, ammonia and water were combined to produce, over a period of time, a number of different amino acids. In addition, a certain amount of the purine, nucleic base, adenine, showed up as a product in this experiment.

"You also discussed how when the foregoing set-up was altered somewhat, other kinds of molecules could be synthesized. For instance, if one combined cyanogen (C₂N₂) and cyanoacetylene (HC₃N) with hydrogen cyanide (HCN), then one could obtain other nucleic bases such as uracil, cytosine, guanine and thymine.

"Finally, in another experiment performed by Oro, you outlined, first, how he took some fatty acids, one of the fundamental building blocks of many important lipids, and, then, how he dried these fatty acids in the presence of phosphate and glycerol. In this manner, simple phospholipids, which are fundamental components of membranes in living organisms, were synthesized.

"I must admit," Mr. Tappin indicated, "on the one hand, I find all of this experimental ingenuity quite impressive. On the other hand, I also find such ingenuity potentially troublesome.

"More specifically, Dr. Yardley, different ingredients are taken from here and there and mixed together in certain ways, for particular lengths of time, under specified conditions of temperature, acidity, and so on. In other words, Professor, the requirements for these experiments are all different from one another, involving, and depending on, different conditions, reactants and treatments.

"Presumably, these experiments are intended to simulate prebiotic conditions and demonstrate how purely natural processes could lead to the synthesis of organic compounds that have potentially important implications for origin-of-life issues. However, just as was true in Miller's original origin-of-life, I'm having trouble understanding how these experiments simulate actual prebiotic conditions and processes.

"For example, Dr. Yardley, do we have any way of telling how prevalent such materials as urea, malic acid, paraformaldehyde, ferric chloride, cyanoacetylene, cyanogen, fatty acids, phosphate, and glycerol would have been in the Archean era?"

"We believe," answered the professor, "that most of the compounds you listed would have been available, some more so than others, during the Archean era. Most of these compounds are extremely simple in structural formula, and we believe they would have been formed relatively easily through natural chemical processes going on during that period of time."

"Dr. Yardley, correct me if I am wrong, but fatty acids are hardly simple hydrocarbons." Referring to the sheets in his hand, he added: "Let's see ... palmitic acid, which is one of the most abundant saturated fatty acids, has a formula of CH₃(CH₂)₁₄COOH. Oleic acid, which is one of the most common unsaturated fatty acids, has a formula of CH₃(CH₂)₇CH:CH(CH₂)₇ - COOH."

"Wouldn't you agree, Professor, that oleic acid and palmitic acid have considerably more complexity than hydrogen cyanide (HCN), ammonia (NH₃) and methane (CH₄)?"

"Yes," Dr. Yardley acknowledged.

"I believe," suggested the defense counsel, "that in your direct examination testimony you said the Fischer-Tropsch reaction was involved in bringing about some of the steps necessary for the formation of fatty acids. Is my recall on this matter accurate, Dr. Yardley?"

"Yes, it is," stated the professor.

"Would you please review, once more, for the members of the jury, Professor, the general nature of the Fischer-Tropsch process," requested Mr. Tappin.

"One takes a gaseous form of carbon, like carbon monoxide (CO)," the professor explained, "together with water vapor, and, then, one passes these over a hot iron-powder catalyst, at temperatures between 180 and 300 degrees Celsius and under anywhere from one to fifty atmospheres of pressure."

"Will one have fatty acids at the end of this process?" asked the lawyer.

"No," replied the professor. "After the foregoing procedure has been run, one must find a way to oxidize the hydrocarbon chains which have been generated by means of the Fischer-Tropsch mechanism."

"In your opinion, Dr. Yardley," asked the defense counsel, "how likely would a naturally occurring counterpart to the Fischer-Tropsch reaction be?"

"The fairest thing I can say," the professor suggested, "is that a naturally occurring counterpart to the Fischer-Tropsch reaction is extremely unlikely but not entirely inconceivable. When one adds to this the requirement of a further oxidation step, one is really pushing the envelope of credibility to the outer limits."

"In the Oro experiment mentioned earlier," indicated the lawyer, "from which phospholipids were synthesized, two further ingredients were needed in addition to fatty acids - namely, glycerol and phosphate. How available were these molecules likely to have been in prebiotic times?"

"This is hard to say. The structural formula for glycerol is C₃H₈O₃ and is normally formed from the decomposition of natural fats by means of an alkali compound or superheated steam.

"There may have been some series of natural chemical reactions during prebiotic times which was capable of synthesizing glycerol. The structural character of this compound is not so complex that the act of assuming the existence of such a hydrocarbon during the Archean era strains credibility.

"A phosphate, on the other hand, is produced by combining an alcohol group with any one of three phosphoric acids. For instance, orthophosphoric acid, which is quite stable, has the formula H₃PO₄.

"Phosphorus, one of the main ingredients of phosphates and phosphoric acids, is a fairly rare non-metallic element. Even at the best of times, there are only trace amounts of phosphorus to be found in seawater, and the presence of phosphorus in the Earth's crust is quite limited relative to elements such as magnesium, iron, calcium, potassium, sodium and silicon.

"Phosphates are very rare in nature, although human beings are quite adept at dumping huge quantities of these compounds into the environment. However, as far as prebiotic times are concerned, there would be no obvious, plentiful source of phosphates, and, therefore, phosphates would not have been readily available to support, in a rigorous fashion, any reaction requiring them during the Archean era.

"This does not mean there were no phosphates in prebiotic times. It merely means their relative scarcity would have placed constraints on where, when and how frequently phosphate-dependent reactions could have proceeded."

"Dr. Yardley, could one fairly say," inquired the lawyer, "that the plausible likelihood of not only producing, but, as well, bringing together, fatty acids, glycerol and phosphates in order to synthesize phospholipid compounds under prebiotic, Archean era conditions is seriously in question?"

"Yes," the professor agreed, "I think one would not be unfair if one were to characterize the situation in this fashion. This doesn't necessarily mean the whole thing is completely impossible, but at this point in time, in the light of what is known, many researchers can't imagine any series of plausible steps during prebiotic times which, A, would have led to the formation of the individual reactants involved in phospholipid synthesis, or, B, would have resulted in these ingredients coming together to make such a reaction possible."

"Therefore," reasoned the defense counsel, "to call Oro's phospholipid synthesis experiment a simulation which accurately reflects what went on under the Archean era's prebiotic conditions is really, potentially, quite misleading. Would you agree with this, Dr. Yardley?"

"Let's just say," the professor offered, "the indicated potential to be misleading is present, and one cannot treat the natural, prebiotic synthesis of glycerol, phosphates, fatty acids or phospholipids as foregone conclusions. At best, the issue lends itself to being highly contentious and argumentative."

"Dr. Yardley, let's return to the Fox polymerization experiment for a moment," Mr. Tappin suggested. "A recipe was used in that experiment which called for a variety of amino acids to be thrown into a mixing bowl of sorts. Subsequently, these ingredients were heated for some 3-4 hours in an oil bath at 170 degrees Celsius.

"In your direct examination testimony, Professor, you indicated many researchers believe the exposed surface of a sandy beach, or a mineral bed, or a strip of solidified lava, where temperatures may have reached up to 100 degrees Celsius, might have served as a crucible for certain condensation reactions during the Archean era. In another portion of your testimony, you spoke about hydrothermal vents in which the temperatures were in the vicinity of 350 degrees Celsius, but these took place under water, not in oil.

"You didn't specifically speak about the conditions around volcanoes in your testimony, Professor. Yet, since neither of the previously-mentioned possibilities really matches the required conditions of the Fox experiment, can one assume that, perhaps, the area in and around certain volcanoes is the only other candidate which, conceivably, might fit into the kind of scenario which Fox's protenoid experiment is purporting to simulate?"

"Volcanic areas," the professor said, "seem to be the only possibility which comes readily to mind."

"Would you agree, Dr. Yardley," inquired the lawyer, "that finding a place in volcanic areas that provided an oil bath of precisely 170 degrees Celsius for just 3-4 hours would be ...let's be kind here ... a tricky project?"

"Yes," responded the professor, "I guess one might not find many places capable of meeting these precise conditions, but this is not the same thing as saying that these sort of conditions couldn't, or didn't, exist."

"Professor Yardley, in your testimony concerning the Fox experiment, you mentioned, I believe," recalled the defense counsel, "that not all of the bonds which linked together the amino acid monomers or units were peptide in character - that only some of these bonds were peptide in character. Is this correct?"

"Yes," the professor replied.

"In living organisms on Earth, peptide bonds," the lawyer stipulated, "occur between the amino and carboxyl groups of neighboring amino acids, binding them together to form proteins. Isn't this so, Dr. Yardley?"

"That's right," the professor confirmed.

"Therefore," concluded the defense counsel, "the amino acid polymers or chains in Fox's experiment are not really proteins because they are not what we find in living organisms. Presumably, for precisely this reason, the polymers in Fox's experiment are called protenoids and not proteins. Is this a fair way of putting things, Dr. Yardley?"

"I guess so," admitted the professor.

"Did any of these protenoids exhibit substantial enzymatic characteristics?" inquired Mr. Tappin.

"Not really," the professor stated. "On the other hand, there might not be anything which prevents protenoids from playing the other major role of proteins involving the morphology or form and structure of organisms.

"Conceivably, a variety of ribozymes - that is, polymers of RNA with enzymatic properties - may have served as the early enzymes of the protocell. Protenoids could have filled the function of helping to give form to these protocells or to various organelles, such as ribosomes or mitochondria, within the protocell."

"Is it not the case, Dr. Yardley," queried the lawyer, "that the bonds, whether peptide or otherwise, formed during condensation reactions, in which water is removed from neighboring monomeric amino acids and, therefore, which are called anhydride bonds ... isn't it the case these anhydride bonds are quite labile and, relatively speaking, easily broken."

"Yes, under certain conditions, this is true," the professor acknowledged.

"Would you agree, Dr. Yardley," asked Mr. Tappin, "that volcanic areas in which temperatures are 170 degrees Celsius, or higher, for prolonged periods of time, might be considered to have met the requirements alluded to by you through your use of the qualification: "under certain conditions", with respect to the labile nature of peptide bonds among amino acids?"

"Yes," admitted the professor.

"Are we not encountering here," wondered the lawyer, "yet another instance in which, under certain conditions, energy may be coupled to chemical reactants for short periods and in specific ways, to forge more complex arrangements of hydrocarbons, but when, under other circumstances, these same forms of energy can quickly turn the tables on the products of such reactions and, as a result, undo what these energy forms previously had helped to bring about?"

"Yes, this is a possibility," the professor agreed.

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