This paper is about 6 theories of how the world began. This includes: The primordial soup theory, the iron-sulfur theory, RNA world theory, deep sea vent theory, community clay theory, and the panspermia theory. Each theory is a different hypothesis on how life on earth began throughout the course of over 1,000 years. ORIGINS OF BIOMOLECULES RESEARCH PAPER Primordial Soup Hypothesis Alexander Oparin (introduced hypothesis) and Robert Shapiro (summarized paper) presented the primordial soup theory in 1924. 3. 8 billion to 3. 5 billion years ago life began in a pond or ocean as a result of the combination of chemicals from the atmosphere and some form of energy to make amino acids, the building blocks of proteins, which would then evolve into the first species on Earth.
Some evidence presented by them includes: 1. The early Earth had a chemically reducing atmosphere. 2. This atmosphere, exposed to energy in various forms, produced simple organic compounds (“monomers”). 3. These compounds accumulated in a “soup”, which may have been concentrated at various locations (shorelines, oceanic vents etc. . 4. By further transformation, more complex organic polymers – and ultimately life – developed in the soup. An experiment was done by a graduate student, Stanley Miller, and his professor, Harold Urey, performed an experiment that demonstrated how organic molecules could have spontaneously formed from inorganic precursors, under conditions like those posited by the Oparin-Haldane Hypothesis. Iron-Sulfur World Hypothesis The idea for the iron sulfur theory of the origin of life was put forward by Gunter Wachtershauser between the years 1988 and 1992.
Linking with the idea of hydrothermal vents being a ‘reactor’ for RNA, hydrothermal vents are a unique productive sphere of the ocean floor. They rely on chemical energy from geothermal vents to sustain a complex range of organisms. Swarms of bacteria thrive in this environment which acts as an interface between the high temperature vents and cold oxygenated seawater. The bacteria thrive on gases produced by the vents such as methane and use these chemicals to produce simple organic molecules to support the local ecosystem in a similar way to plants using photosynthesis.
Wachtershauser has prop sed that a biochemical cycle grew and assembled the first living cell. In this experiment, the chemical coupling of iron salt and hydrogen sulfide from the hydrothermal vents produced pyrite. Simple compounds will accumulate on the surface of the pyrite and molecules such as CO and organic acids and sugars will also accumulate on the surface. In this way, the system does not use any cellular components and starts from a compound – pyrite – which was abundant in early Earth’s oceans.
RNA World Hypothesis The RNA world, first posited by Francis Crick in the late 1960s. A popular theory amongst scientists of an RNA world where life begins with self-replicating RNA molecules, has emerged from the theory of the primordial soup which is explained in the area of spontaneous generation. According to the RNA world theory, RNA molecules are said to have powered their own replication and through selection pressures evolved into the more chemically stable DNA strands which took over data storage of genetic material.
The RNA world theory suggests that RNA in modern cells is an evolutionary artifact of the RNA world. At first glance there would appear to be logic in this theory based on RNA’s important position in modern organisms. A number of molecular biologists have shown that RNA can function as an enzyme and directly catalyze the 4 ORIGINS OF BIOMOLECULES RESEARCH PAPER formation of bonds to hold the RNA and DNA structure together.
If a primitive molecule of RNA was able to catalyze its own self replication it could eventually evolve through natural selection into more efficient structures that might incorporate other primitive compounds such as protein into this early system. The evolution of RNA molecules has been demonstrated by scientists in RNA viruses. Under the correct environmental conditions which require a quick replication, the RNA strand will, given an adequate supply of building blocks and starting enzymes, become smaller as selection acts for maximum reproductive speed.
Deep Sea Vent Hypothesis Introduced by Gunter Wachtershauser in 1988 the deep sea hypothesis is a similar chemosynthetic process to the one observed on the Galapagos Hydrothermal Vent Expedition had been around on Earth for a very long time. Not only was it common to the planet Earth throughout its history, he argues, this process was fundamental to all living ecosystems going back to the very first genesis of life around four billion years ago. His origin-of-life premise is called the Iron-Sulfur Theory.
It posits that hot, pressurized water mixed with dissolved gases (including hydrogen sulfide, carbon monoxide, carbon dioxide, hydrogen cyanide and ammonia) passed out of prehistoric vents and over various minerals containing iron, nickel and other metals within the rocks around the vents. These metals served as catalysts for a chain reaction that synthesized organic compounds and coupled some of them with other metals to form new compounds with greater ability to yield new chemical reactions.
This coupling between the catalyst and the product of an organic reaction is the key first step of Wachtershauser’s theory. What comes next is the miracle of evolution. Starting with these metals and gases reacting together as life emerged, Wachtershauser says evolution starts with the beginning of a primitive metabolism that created increasingly complex chemical reactions, eventually leading over time to the formation of DNA — life’s blueprints for making more living cells today.
Community Clay Hypothesis In 2013 Dan Luo, of the Kavli Institute at Cornell for Nanoscale Science,and his team found a compound used for creating life in a sample of clay they were using when looking for inexpensive hydrogels that could be used to produce proteins on a largescale. In the study, scientists speculate that clay hydrogels provided a platform for chemicals to come together and form complex biomolecules. Experiments using water samples that resemble ancient seawater have shown that clay forms a hydrogel under certain conditions.
Hydrogel is a network of polymer chains that has the ability to soak-up huge quantities of water. Basically, these gels are super-sponges. Over billions of years, the trapped chemicals reacted and formed biochemicals such as proteins and DNA. Panspermia Hypothesis The first known mention of the concept of panspermia was in the writings of the Greek philosopher Anaxagoras (500 BC – 428 BC). The panspermia hypothesis states that the “seeds” of life exist all over the Universe and can be propagated through space from one location to another.
Some believe that life on Earth may have originated through these “seeds”. Several tests 5 ORIGINS OF BIOMOLECULES RESEARCH PAPER for organic material have been performed on ALH84001 and amino acids and polycyclic aromatic hydrocarbons (PAH) have been found. However, most experts now agree that these are not a definite indication of life, but may have instead been formed abiotically from organic molecules or are due to contamination from contact with Antarctic ice. The debate is still ongoing, but recent advances in nanobe research has made the find interesting again.
All things have existed from the beginning. But originally they existed in infinitesimally small fragments of themselves, endless in number and inextricably combined. All things existed in this mass, but in a confused and indistinguishable form. There were the seeds (spermata) or miniatures of wheat and flesh and gold in the primitive mixture; but these parts, of like nature with their wholes, had to be eliminated from the complex mass before they could receive a definite name and character. ” The quote from Anaxagoras bringing in his thoughts.