RNA World Theory: Summary and Analysis

RNA World Theory: Summary and Analysis This essay will explore the principles of the RNA world theory and supports and criticisms for it. It will look at the properties of RNA which make this theory viable and it will also look briefly at alternate competing theories. RNA, which stands for ribonucleic acid, is a polymeric molecule made up of one or more nucleotides. Each nucleotide is made up of a base: adenine, cytosine, guanine, and uracil, a ribose sugar, and a phosphate which can then form chains. Like DNA, RNA has four main structures: primary, which is the basic polypeptide chain. The Secondary structure is a twisted form of the chain into usually an alpha helix and beta sheet. The tertiary structure is a further folded shape and is often unique. This structure determines the function of the protein. Finally the quaternary is the joining together of multiple tertiary subunits to form one large subunit. The discovery of ribozymes supported the RNA World Hypothesis. This is the theory that earlier life forms may have relied solely on RNA to catalyse chemical reactions and store genetic information. This hypothesis was proposed by Carl Woese, Francis Crick and Leslie Orgel in the 1960s, this was decades before the discovery of ribozymes but soon after the double-helical structure of DNA was determined. According to the RNA World Hypothesis, life later evolved to use DNA and proteins due to RNAs instability relative to DNA and its poorer catalytic properties. Gradually, ribozymes became increasingly phased out. A ribozyme, ribonucleic acid enzyme, is an RNA molecule that is capable of performing specific biochemical reactions, similar to the action of protein enzymes. The structure of RNA nucleotides is very similar to that of DNA nucleotides, with the main difference being that the ribose sugar backbone in RNA has a hydroxyl group that DNA does not. Another minor difference is that DNA uses the base thymine in place of uracil. Despite great structural similarities, DNA and RNA play very different roles from one another in modern cells. RNA plays a central role in the pathway from DNA to proteins, known as the Central Dogma of molecular biology. An organisms genetic information is encoded as a linear sequence of bases in the cells DNA. During transcription, an RNA copy of a segment of DNA, messenger RNA (mRNA), is made. This strand of RNA can then be read by a ribosome to form a protein. Another major difference between DNA and RNA is that DNA is usually found in a double-stranded form in cells, while RNA is typically found in a single-stranded form. The lack of a paired strand allows RNA to fold into complex, three-dimensional structures. RNA folding is typically mediated by the same type of base-base interactions that are found in DNA, with the difference being that bonds are formed within a single strand in the case of RNA, rather than between two strands, in the case of DNA. The strongest evidence for the RNA World Hypothesis is the fact that the ribosome, a large molecular complex that assembles proteins, is a ribozyme. Although the ribosome is made up of both RNA and protein components, structural and biochemical analyses revealed that the mechanisms for translation is catalysed by RNA, not proteins. This suggests that the use of RNA by early life forms to carry out chemical reactions may have preceded the use of proteins. John Sutherland and his colleagues from the University of Manchester performed and experiment that greatly supports the RNA world hypothesis. He and his team created a ribonucleotide, which is a major part of RNA, from simple chemicals. These chemicals are those though to be present on the early earth, or primordial soup. Donna Blackmond, a chemist at Imperial College London, stated that this is extremely strong evidence for the RNA world. We dont know if these chemical steps reflect what actually happened, but before this work there were large doubts that it could happen at all. Critics of these ideas suggest that other organic molecules, rather than nucleic acids, were the first self-replicating chemicals capable of storing genetic information. According to this idea, these simple hereditary systems were later replaced by nucleic acids during the course of evolution. Electric Spark Generation of amino acids and sugars from the atmosphere. The  Miller-Urey supports this theory. The experiment in 1952 was one  that simulated the conditions thought at the time to be present on the  early Earth, and tested for the occurrence of  the chemical origins of life. Miller took molecules which were believed to represent the major components of the early Earths atmosphere and put them into a closed system. The gases they used were methane (CH4), ammonia (NH3), hydrogen (H2), and water (H2O). Next, he ran a continuous electric current through the system, to simulate lightning storms believed to be common on the early earth. Miller observed that as much as 10-15% of the carbon was now in the form of organic compounds. Two percent of the carbon had formed some of the amino acids which are used to make proteins. Millers experiment showed that organic compounds such as amino acids, which are essential to cellular life, could be made easily under the condi tions that scientists believed to be present on the early earth. Community Clay The first molecules of life might have met on clay, according to an idea elaborated by organic chemist Alexander Graham Cairns-Smith at the University of Glasgow in Scotland. These surfaces might not only have concentrated these organic compounds together, but also helped organize them into patterns much like our genes do now. Chilly Start As the sun was about a third less luminous than it is now. This layer of ice, possibly hundreds of feet thick, might have protected fragile organic compounds in the water below from ultraviolet light and destruction from cosmic impacts. The cold might have also helped these molecules to survive longer, allowing key reactions to happen. Simple Beginnings Instead of developing from complex molecules such as RNA, life might have begun with smaller molecules interacting with each other in cycles of reactions. These might have been contained in simple capsules akin to cell membranes, and over time more complex molecules that performed these reactions better than the smaller ones could have evolved. Panspermia Rocks regularly get blasted off Mars by cosmic impacts, and a number of Martian meteorites have been found on Earth that some researchers have controversially suggested brought microbes over here, potentially making us all Martians originally. Other scientists have even suggested that life might have hitchhiked on comets from other star systems. There is no scientific evidence to suggest that RNA is spontaneously being created and capable of forming pre-cellular life today. While some artificial ribozymes have been created in the laboratory (reviewed in Chen, et al., 2007), there are still significant holes in reproducing an RNA world to support the hypothesis. The ribozymes created artificially lack the abilities to sufficiently process themselves, and there is no evidence of them producing large quantities of advantageous nucleotide sequences. Moreover, no system has ever created cellular life. There is even significant debate among scientists over the conditions and constituents of a prebiotic Earth model.

Hinduism and Buddhism Essay

In recent years, numerous Eastern philosophical thoughts have influenced the contemporary world in more ways than one. Eastern philosophy serves as the foundation of discipline and way of life for most Asians and even several individuals from the west . The significance of eastern influences not only incline on the purpose of commemoration of historical people but on the scrutiny of principles and doctrines that contribute to growth as well. In a strict sense, eastern philosophies have connections in one way or another and such connections are often found in the beliefs and practices of such schools of thought. Hinduism and Buddhism for instance are regarded as two of the oldest systems of discipline both in doctrine and practice (Moore & Bruder, 2005). These philosophies are two of the oldest in the Dharmic tradition, hence it is plausible for Buddhism and Hinduism to be the subject of comparison. Hinduism is the oldest major religion still practiced today, it traces its roots from unrecorded history. The doctrines of Hinduism are as diverse as its number of interpretations, as such, Hinduism per se is more of a spiritual attitude that spawns an array of religious and philosophicl beliefs and traditions (Moore & Bruder, 2005). The diversities come in different forms such as worship of elements in the form of any living entities up to cultured metaphysical theories (Moore & Bruder, 2005). The diversities of hinduism, conversely, are bound by the Vedic scriptures’ authority, these scriptures are the basis of understanding for the discreet natural state of things (Moore & Bruder, 2005). Buddhism on the other hand is a system of beliefs, originally from Siddhartha Gautama (Buddha), that responds to the supposed predicaments brought about by suffering which extends its arm to the feelings of sorrow, dissapointment, frustration, discontent, disaffection, pessimism and unfulfillment (Moore & Bruder, 2005). Buddha narrows the resolution to suffering in the context of his four noble truths: There is Suffering, Suffering has its causes, suffering has an end and there is a way to end suffering in the eight-fold path (Moore & Bruder, 2005). Hinduism and Buddhism both believe in the cause and effect principles of Karma. Karma’s is encompassed on the idea that intentions are the measuring factors of a person’s deeds. In Karma, these deeds will be carried over for several lifespans through an individual’s incarnations depending if a deed is morally good or morally bad (Moore & Bruder, 2005). Another element similar to Buddhism and Hinduism as the principles is Nirvana, though defferences are evident in the ways and means, the two are both directed to the attainment of the latter. Nirvana is a sanskrit word that literally means extinction and is applied in Buddhism and Hinduism as freedom from the cycle of life, death and reincarnation (Moore & Bruder, 2005). Personally, I concur to the system of beliefs suggested by Buddhism, primarily because it provides an easy, step-by-step guide to the achievement of the goal, nirvana. Gautama’s teachings, though hard and require discipline is the perfect path to enlightenment given that he primarily insinuates worldly desires and other emotions that hinder an individual from discovering the true self. Moreover, Buddha implies simplicity of Buddhist practices in the sense that he himself noted that anyone can achieve the insights that he had via focus, sincere meditation, continuous elimination of worldly desires and freedom from egoistic thoughts, fear and anxiety.

Meaning of Kisetu in Japanese

Kisetsu is a Japanese word meaning a season or certain time of year. Learn more about its pronunciation and usage in the Japanese language below. Pronunciation Click here to listen to the audio file. Meaning a season; the time of the year Japanese Characters Ã¥ ­ £Ã§ ¯â‚¬ 㠁 Ã£ â€ºÃ£  ¤ Example Translation Dono kisetsu ga suki desu ka.㠁 ©Ã£  ®Ã¥ ­ £Ã§ ¯â‚¬Ã£ Å'Ã¥ ¥ ½Ã£  Ã£  §Ã£ â„¢Ã£ â€¹Ã£â‚¬â€š or in English: Which season do you like?

Concert Report Mozart Essay - 1032 Words

Tannya Trudeau 4135080 Professor Grant Musi200 D004 Fall10 15 January 2011 Concert Report: Mozart Symphony No. 40 The western classical concert that I have chosen to review is A Tale of Two Symphonies. This concert is performed in the Avery Fisher hall within the Lincoln Center in New York City. It was performed on July 29, 2008. The orchestra that is performing is the 42nd Mostly Mozart Orchestra. The conductor is Louis Langrà ©e. The two pieces being performed in this concert is Mozarts Symphony No. 40 and Mahler’s Das Lied von der Erde. The first piece that was played was Mozart’s Symphony No.40. This is a beautiful piece of music. There are 38 players in the orchestra for this piece. And they all played†¦show more content†¦I feel that the fourteen members of chamber orchestra and the two vocalists did an outstanding job. This piece was well put together. I loved the harmony that was brought forth between the orchestra and the vocalists. The two vocalists a tenor known as Paul Groves and a soprano known as Anna Larson, did a b eautiful job staying in tune. The way that their voices went back and forth in harmony was just beautiful. Although I enjoyed both pieces of music I really enjoyed the works of Gustav Mahler and his piece Lied von der Erde. This piece is rich in drama. I feel that the texture used is this song is imitative polyphony. I feel that there are various parts in this song that use the similar melodies. I feel that the harmony between the two vocalists were right on with each other and the orchestra. You can hear the brass instruments in the very beginning of the songs then the strings, wind instruments along with the piano and keyboards begin to make their entrance. They come together very strong but in a peaceful way at first. Towards the middle of the song the tempo and rhythm really picks up (it seems as if all of their emotions are bursting out) then it slowly begins to drop back to slower movements. You can really hear the strings during this time. But surprisingly enough just when yo u think the song is going to end boom your hit again. This song keeps you on the edge of yourShow MoreRelatedConcert Report On Music Concert1143 Words   |  5 PagesName Music32 Concert Report Professor Name 2015.6.2 Music Concert Report On Sunday, May10 2015, a concert was held in The Broad Stage. The concert was played by Santa Monica College Symphony Orchestra, whose conductor is Dr. James Martin. For this concert, I would identify myself as a referential listener at this concert. I say this becauseRead More wolfgang amadeus mozart Essay1190 Words   |  5 Pages Mozart was considered to be the best musician/composer of all time. 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