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On Life: Its Origin and Elements Research Assignment (Essay Sample)



On Life: Its Origin and Elements
The origin of life is a problem that has not been entirely closed up until this day. There are definitely several theories on how life came about. With these, however are only a few known facts. The current paper explicitly reviews the several theories on the origin of life. Towards the end, it analyzes life’s known elements.
Theories on the Origin of Life
Primordial Soup
Since the beginning of the nineteenth century, scientists have been doing their best to correctly address the issue of life’s origin. One of the most consequential theories was developed by Ernst Haeckel. According to Haeckel, primeval organisms were heterogeneous. In addition, he postulated that lumps of protein are developed when sea materials and external forces interact.1 With the advent of more studies on the DNA molecule, theories have started to change. Reproductive methods in the molecular sense were found out to be alike. Such uniformity changed the game of life origin theories.
The primordial soup hypothesis, currently the most famous theory on the origin of life, suggests that nucleic acids and proteins coexisted in a warm and aqueous earth. In his experiment, Aleksandr Oparin found out that amino acids can spontaneously form in a controlled environment modeled after the primordial soup.2 In essence, this theory suggests that the first species on earth resulted from interaction between chemicals in the atmosphere and energy. This pertains to energy as found in the physical external forces of the world.
To simplify the primordial soup theory, it basically focuses on four basic principles. Firstly, the hypothesis suggests that the earth then had an atmosphere with tons of reducing chemicals. Secondly, this atmosphere is exposed to various forms of energy, thus forming monomers or simple organic compounds. Thirdly, the compounds accumulated in a so-called “primordial soup.” Lastly, further transformation into more complicated polymers later develops in this primordial soup, thus causing the advent of life.
One of the earlier experiments that further explored this theory was conducted in 1953. Stanley Miller, with the help of Professor Harold Urey, conducted an experiment that replicated Oparin’s findings. In the Miller-Urey experiment, they were able to demonstrate how organic molecules form from precursors that were rather inorganic. In the experiment, highly reduced gases in the form of methane (CH4), ammonia (NH3) and hydrogen (H) were used to form monomers. This, of course, coincides with the first two tenets of the primordial soup hypothesis.
While this suggestion on the origin of life seems like a plausible process, like any proposition that centers on abiogenesis, it has faced a lot of criticism. For instance, compounds that may prohibit polymer-formation were actually formed in the Miller-Urey experiment. Specifically, there were substances that underwent cross-reactions that later eradicated the peptide chain. In addition, a fundamental argument of how a monomer turns into a protocell remains unfathomed. For instance, in a relatively aqueous environment, polymer hydrolysis into monomers is actually more likely than condensation of monomers into polymers.
RNA World Hypothesis
Before going in depth on the RNA world hypothesis, a broader context of the discovery of ribozymes is vital. Proteins in cells are essentially catalysts of chemical reactions that are important for cells to survive. These catalyzing proteins are called enzymes. For a long time, the scientific world was under the impression that proteins are the only biological molecules that have catalyzing capabilities. Recently, however, Sidney Altman and Thomas Cech were able to find out that RNAs also have such abilities. These RNAs with catalyzing capacity are called ribozymes.
The discovery of these catalyzing RNAs supported the RNA World Hypothesis. This theory relies on RNA alone for gene storage and catalyzing of chemical reactions. It came about slowly after the discovery of the DNA structure. The said hypothesis acknowledges that RNA is relatively unstable, thus it credits life’s later evolvement to DNA and proteins. The strongest evidence for this hypothesis is the simple fact that ribosome is a ribozyme. A typical ribosome is made up of RNA and protein. Interestingly, translation has been found out to be catalyzed by RNA, rather than protein. This, in itself, suggests that RNA is definitely used for catalyzing in early life forms.
There are problems, however, that come with this theory. For one, it is true that RNA can perform a substantial amount of functions in a cell. However, there is no evidence to this day that supports it being able to carry out functions of proteins. In addition to this, the RNA world hypothesis also fails to address how exactly genetic information originated. For RNA to evolve into DNA, genetic information must then be capable of evolving into proteins. This process, though, requires heavy transcription and translation that themselves need genetic information to be encoded. It is a chicken-and-egg problem, with no sufficient argument that with no direct and precise answer to this day. Furthermore, proponents of this hypothesis say that life is based on RNA. They say there is a requirement for a molecule of 200-300 nucleotides in order for all to have arisen. However, there are no known laws that dictate these nucleotides.
One possibility of life’s origin that centers on a more scientific fiction approach is the panspermia theory. This theory suggests that life on earth did not start on our planet. On the converse, life here was simply transported from another place in this universe. While this idea seems far off, there are actual scientific evidences that support extraterrestrial origin of life.
The main support of the panspermia theory is life’s emergence shortly after the earth was heavily bombarded 4 – 3.8 billion years ago. During this time, the earth is believed to have endured numerous heavy meteor showers. Interestingly, the earliest evidence for life on earth dates back to 3.83 billion years ago, which coincides with the bombardment phase.3 In order for life to originate in another planet, there is obviously a need for a place that can support life. Current studies of the universe, however, show that surviving outside the Earth is impossible. However, parallelly, it should be noted that there are bacteria that can survive intensely cold or hot habitats. Some can even be preserved in liquid nitrogen, can tolerate UV radiation and can survive extreme pressure. All these lead to the suggestion that establishing whether or not a place is befitting for life is almost impossible. What researchers know may be true for humans and animals, but bacteria, which have existed much earlier, are much more adaptable.
Furthermore, the panspermia hypothesis is reinforced by the presence of water in several places in the universe, such as Mars and Europa, one of Jupiter’s moons. Coupled with this evidence is the fact that organic matter is common in space. Organic matter, or matter composed of carbon, suggests life in other planets because on Earth, all living things are carbon-based. If extraterrestrial life were really to exist, one other concern that this theory ought to address is how this reached earth. The theory’s explanation mostly centers on “seeds of life,” as in bacterial spores that allow bacteria to be dormant without nutrients.
An important thing that should be acknowledged about the panspermia hypothesis is that it does not address how life arrived on Earth and how it essentially started. Even if proof on panspermia can be shown, the question of where and how life originated still remains unanswered. The theory merely addresses life on earth, but not life in general.
Electric Spark Theory
The electric spark theory was first put forward by Charles Darwin in his letter to botanist Joseph Hooker. “The original spark of life may have begun in a warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, etc. present, so that a protein compound was chemically formed ready to undergo still more complex changes.”4 This theory believes that when the solar system was formed, an electric spark created primordial matter. It is from this primordial matter that it considers life first came from. There are two versions of this theory. The first one acknowledges that there was “one spark” from which the first form of life came about. The second one, on the contrary, takes into consideration prolonged sparking.
Much of the poof of this theory is credited to Miller and Urey’s experiment as discussed in the primordial soup portion of this text. In the experiment, it was shown that electric sparks can create amino acids and sugars, as long as there is an atmosphere with compounds. Lighting may have helped in generating the blocks of Earth’s life during the early days. Larger molecules may have then formed, consequent to this. However, criticism arises as Miller and Urey’s experiment were not so realistic because the lightnings were continuous, as opposed to how they naturally occur. Truly, amino acids and organic compounds may have formed from lightning, but this is not to the extent of how much was produced in the experiment.
Chilly Start
Yet another theory is that life came from an icy environment. In 1994, researchers proposed that repeated freezing and thawing cycles accelerate chemical reactions. These chemical reactions include those that are necessary for life. Proponents of this theory argue that microscopic portions of water within olden ice have gathered molecules, which then accumulated into longer chains that started life. Life, they believe, started inside extremely large chunk...
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