Evolution From A Molecular Viewpoint Essay
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Evolution from a molecular PerspectiveIntroduction: Why globular evolution?Evolution has been a heavily debated issue since Charles Darwin first documented the theory in 1859. However, until just recently, adaptation at a molecular level has been overlooked except by the scientific world. Now with the help of modern technology, the protein sequences of nearly every known living thing have either been established or are in the process of establishment, and are widely accessible via the internet. With the knowledge of these sequences, one can actually look at several organisms genetic codes and point out the similarities. Entire genomes of creatures have been sequenced, and the human genome project is well underway and ahead of schedule. With this new knowledge comes worries, for humans, however. What if the information stored in our genes was available to the public? Would insurance companies and employers base their selections on these traits? Also, with the total knowledge of every sequence of every amino acid chain in a person's genome, couldn't a laboratory perceivably reconstruct an exact copy of, or clone, that person? These are all issues that will have to be dealt with in the near future, but for now we need only concern ourselves with the objective observation of these proteins in our attempt to explain our ever mysterious origin. As humans, we are the first creatures to question exactly where we came from and how we got here. Some cling to religious creationism as a means, while others embrace the evolutionary theory. As of now, and possibly forever, neither can be proven to be absolute truth with hard facts, and both have their opposing arguments. The point of this paper being composed is not to attempt to abolish the creationist view, a feat that at this point seems impossible, but merely to educate those seeking to unravel the mystery of our forthcoming by pointing out facts that exist in the modern world and that can be quite easily and independently researched. It is conceivable that the two ideas, creationism and evolutionism, can exist symbiotically due to the fact that both views have very good points. Hemoglobin: Comparisons between speciesOf all the proteins in living things, hemoglobin is "the second most interesting substance in the world," as American biochemist L. J. Henderson once stated (Hemoglobin, 4). However bold this statement seems, it must be realized that hemoglobin is, at least in the scientific world, by far the most studied and most discussed substance in the human body, as well as in other living organisms. Hemoglobin is the carrier in blood that transports oxygen to our tissues and carbon dioxide out of our body, changing colors as it does so. Hence, hemoglobin has long been termed the pigment of our blood. Hemoglobin was one of the first proteins to be purified to the point where its molecular weight and amino acid composition could be accurately measured. This finding was very important in that it eventually lead to the understanding that a protein is a definite compound and not a colloidal mixture of polymers. Each molecule was built from exactly the same amino acid subunits connected in the same order along a chain, and had exactly the same weight. Most organisms have their own unique, individual chain of proteins to make up their hemoglobin, but all organisms share certain similarities, so striking that they are unable to be ignored. Let's take, for example, the first twenty-five amino acids in the alpha hemoglobin chains of 7 different animals: a human man, rhesus monkey, cow, platypus, chicken, carp (bony fish), and shark (cartilaginous fish) (See Table 1.1.) As is shown, the variations increase the further apart the organisms are on the proposed evolutionary scale. A human man differs from a rhesus monkey only twice in the first twenty-five amino acids of their alpha hemoglobin chains, whereas a man and a cow differ in three areas. This is the product of many thousands of years of natural fine tuning, if you will, through the slow but precise processes of natural selection and adaptation. The fact of natural selection shows us that while most genetic mutations usually prove fatal, a slim few are actually beneficial, and assist the mutant in living and procreating offspring. This assistance helps the mutant-gene's frequency grow in the gene pool and remain there since all progeny possessing this certain trait are going to have an advantage over the other organisms lacking this quality. This is the basis for evolution. The higher a certain species is on the evolutionary scale, the more advanced that organism is due to a slight change in the amino acid sequences of certain genes. An example would be that of the human man, the rhesus monkey, and the cow. There is a smaller difference in the amino acid sequences between a man and a monkey than between a man and a cow, and, respectively, a monkey is more advanced than a cow, genetically (monkeys and humans have far advanced apposable thumbs.) Also, where the amino acids have been conserved between all the studied organisms, such as in columns 27, 31, and 39, indicates that in order for the species to survive, that certain amino acid must be there. If it is changed in any way, the organism can not survive. There are thirty-four conserved positions in the first 141 amino acids in the seven studied organisms. After just these few demonstrations, how could anyone doubt the theory of evolution? This question leads me into a short interlude where I will discuss the arguments on both sides, and show just how endless this debate could be. Evolution -vs- Creation: Which Is Truth?When evolution is mentioned to many people, the first thing that enters their mind is the completely incorrect thought that man evolved from monkeys. Man did not, in fact, evolve from monkeys, this is a known and agreed upon fact. The only connection between modern day men and modern day chimpanzees, for example, is the fact that they must have shared a common ancestor. The "common ancestor" theory, as I have chosen to name it, states that all life living, or ever to have lived on this planet can be traced back to a single, common ancestor. At some point in time, between 3.5 and 4.1 billion years ago, a certain grouping of chemicals came together at just the right time and life began. From this single life-form, the slow process of natural selection began. First came the proteinoid microsphere, the first organisms on the planet to carry on all life functions. Eventually, then, came viruses, parasites, saprophytes, holotrophs, chemosynthesizers, and photosynthesizers, all mutants of the very first cell. Some have tried to use thermodynamics to disprove evolution, especially the second law. The second law of thermodynamics states that "all energy transfers or transformations make the universe more disordered." These speculatives claim that since man is more advanced than any other creature, we are more ordered. This is wrong. Man is more advanced due to the mutations in his genes. Compared to the very first life-form's genes, a human man's amino acid sequences are very dissimilar, or more disordered. Also, the first law of thermodynamics can be used for either argument. The first law of thermodynamics states that energy cannot be created or destroyed--in other words it has always been here. Using this law, the matter in the universe can either be thought of as always being here, or that the creator, with his infinite power, simply transformed the energy that he possessed into the matter of the universe. Both sides have an arguable point that agrees with the laws of thermodynamics. Another arguable point that is worthy of mention is the discrepancies in the fossil record. The Earth's crust, and all the fossils contained therein, can also be utilized as arguments for both sides. The "Pre-Cambrian Void" (Creation-Evolution: The Controversy, 362) shows very little sign of fossilization. Then, suddenly, massive amounts of fossilization can be found during the Cambrian times, pointing to some sort of catastrophe, like a flood. The Bible mentions a flood sent by God to destroy every living thing on Earth. The fact that a flood could have happened, in that sense, strengthens the creationists' views. The evolutionist theory can use these facts in two ways. One, when the selection pressure on a species is constant for a long time, a species could become so specialized that any slight change in their environment could lead to extinction, this is called a climax group. Around the time that the large amounts of fossilization was occurring, the Earth had cooled down enough to allow the immensely dense atmosphere to condense, thus causing many years of rain. Would not this rain cause almost any climax group's entire population to become extinct? Also, before the rains came, the great majority of the organisms inhabiting the Earth were land creatures. Once the rains came, the Earth was covered in water, killing thousands of populations, and effectively burying them in the water. The water preserved their parts for fossilization. These have been just a few double sided arguments demonstrating that either side can turn any facts around to fit their own hypothesis. Leghemoglobin, Protein Relations Between Species, and the Evolution of the Globin FamilyLike animals, plants also carry a sort of hemoglobin, leghemoglobin. Leghemoglobin is a globin which is less evolved than that of hemoglobin or myoglobin. The whole globin family, itself, has undergone much evolution and mutation. At one time, animals had no globin at all. As life evolved, a single-chain oxygen-binding substance formed--we will call this the basic globin. Then life branched into two parts: animals carrying the basic globin, such as annelid worms, insects, and mollusks, and creatures (manly plants) carrying leghemoglobin, a mutation of the basic globin. The animal kingdom's globin eventually split into myoglobin (Mb) and hemoglobin (Hb). Since then, myoglobin has basically stayed the same in many organisms (See Table 1.3.) Hemoglobin, on the other hand, has undergone some major mutations. After the basic globin bifurcated into Mb and Hb, Hb split into alpha (a) and beta (b) chains. The a-chain eventually split into two parts, and has remained this way up to present times. The b-chain split into many more parts. Everything that has been said up until now about the evolution of the globins from a common single-chained oxygen-binding ancestor has been summarized in Table 2. If one would compare sequences of globin between species, one would notice that the less amino acids that are different the more closely related two species are. If we used this theory on the vertebrates that were studied it would give us a "schematic family tree of globin containing vertebrates" (Hemoglobin, 78) (See Table 3). This same tree is obtained by comparing sequences of myoglobin, or the a or b chains of hemoglobin. This tree tells us that all organisms...
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