Rna World : A Possible Theory For Life Origin

• *Compare and contrast the structure and function of DNA and of RNA molecules. Reference Table 4.1.

Transcription is the formation of an RNA strand from a DNA template within the nucleus of a cell. There are four nucleotides of DNA. These are adenine, cytosine, guanine and thymine. These nucleotides are transcribed to form messenger ribonucleic acid (mRNA) consisting of nucleotides made of adenine, cytosine, guanine and uracil. This transcription from DNA to mRNA happens by an RNA polymerase II. This newly created mRNA is read in the 5' to 3' direction in sets of 3. These sets are called codons. Each mRNA also has a cap and end. On the 5 prime side is a methylated guanine triphosphate and on the 3 prime is a poly A tail. Messenger RNA then moves to the cells cytoplasm and through the cells ribosomes for translation. Messenger RNA is matched to molecules of transfer RNA (tRNA) in the ribosomes to create amino acids. These amino acids subsequently form an amino acid chain. (Osuri, 2003) A visual representation of this can been viewed in figure 3.

After the DNA has been turned into mRNA a process called translation occurs and it turns the mRNA into tRNA.

5. RNA developed before DNA because RNA could have been small and still would exist if it was able to fold into a more stable formation. The sequences that folded into a stable formation would be more likely to survive and duplicate that sequence.

RNA processing: In eukaryotic cells, introns, non-coding regions of RNA, are removed and a tail and a cap is added to RNA to help its movement.

3. A strand of DNA serves as a template (model) for the synthesis of RNA molecules.

Peter Nielson, along with many other scientists, have spent years creating and experimenting with a synthetic molecule called peptide nucleic acid (PNA). PNA is an artificial polymer that has many similarities to deoxyribonucleic

Although early Earth was hostile, it provided a great environment for the production of organic molecules. Events such as lightning, volcanic eruptions, meteorites, radioactivity in the Earth’s crust, and the easy access of ultraviolet light, are thought to have provided the energy for these molecules to produce. Therefore, the conditions of early Earth were critical in the commencing of the first organic molecules.

ends when the RNA polymerase reaches a triplet of bases then the DNA molecules re-

Translation is the process in which ribosomes synthesize proteins using the mRNA transcript produced during transcription. AT first, the mRNA binds with a ribosome so that it can be decoded one codon at a time. Each codon codes for an amino acid is activated. A tRNA molecule has two ends: one that has a specific binding site for a particular sequence of nucleotides, an anticodon that can base pair with a codon. Appropriate tRNA molecules attach to, then carry the activated amino acid to the ribosome. Anticodons air with codons to bring the specific amino acid to the correct place. A second tRNA repeats this process and the first tRNA releases its amino to the second tRNA. The two amino acids form a peptide bond using the energy from ATP. The ribosome reads the next codon and then another tRNA comes along to repeat the process. As tRNA come and go, amino acids link together, forming more peptide bonds. Eventually, a polypeptide chain in synthesized and it undergoes its conformational changes to carry out its function as a protein. DNA Replication and protein synthesis are both similar and

According to astronomical research and geological evidence, scientist indicate the universe is approximately thirteen thousand eight hundred and twenty billion years old. The first link to humanity started with a primate group called Ardipithecus. While our ancestors have been around for about six million years, the modern form of humans only evolved about two hundred thousand years ago. The age of the Earth is estimated about four point fifty four billion years because that is the age of the oldest rocks with fossil evidence of life on earth. The oldest rocks on Earth found to date are the Acasta Gneisses in northwestern Canada near the Great Slave Lake, which are four point three billion years old. The study of the origin of life on Earth, more specifically abiogenesis, is the natural process of life arising from non-living matter. Life on Earth is believed to have began from organic compounds about three point eight to four billion years ago. Despite several competing theories for how life arose on Earth scientist only know when life first appeared on Earth and are still far from answering how it appeared. Since it is hard to prove or disprove them, no fully accepted theories of the origin of life exists.

One of the fundamental discoveries of the 20th century was that DNA was the genetic code’s physical structure (Watson & Crick, 1953) and, since then, many studies have disclosed the complicated pattern of regulation and expression of genes, which involve RNA synthesis and its subsequent translation into proteins.

Transcription is where DNA is transcribed into RNA which then can be pass to the ribosome’s to act as a template for protein synthesis. Before transcription can begin DNA must unwind and the two halves of the molecule much come apart so exposing the base sequence. This process begins when a region of a two DNA strands is unzipped by enzyme called RNA polymerase attaches to the DNA molecule at the imitation site.

One of the main theories is that life started by chemical means in a rock where water, methane, ammonia and hydrogen were all present then with the added effect of lightening simple organic molecules formed the building blocks of life. There was an experiment that was conducted in 1953 by Miller and Urey that supports that the conditions above could stimulate organic compounds to form. *copied “ The Miller-Urey experiment attempts to recreate the chemical conditions of the primitive Earth in the laboratory, and synthesized some of the building blocks of life.

The formation of a protein begins in the genes, which contain the basic building information for all parts of living organisms. There are four DNA nucleotides that make up genes: A, T, C, and G. A codon is any arrangement of three of these nucleotides. Each triplet of nucleotides codes for one amino acid. First transcription will begin in the nucleus where mRNA will transcribe the DNA template. During both transcription and translation, there are three steps. The first step in transcription is initiation where RNA polymerase separates a DNA strand and binds RNA nucleotides to the DNA. RNA nucleotides are the same as DNA ones except that U replaces the T. The second is just the elongation of the mRNA. The third step of transcription is termination. This occurs when RNA polymerase reads a codon region and the mRNA separates from the