Post #5084

How did life begin on Earth? New experiments support 'RNA world' hypothesis RNA, which is one of life's most crucial molecules dealing with the synthesis of proteins, could be common in the universe, according to a new experiment that shows how RNA could easily have formed on Earth 4.3 billion years ago. RNA (short for ribonucleic acid) is a simpler cousin of DNA, which is the molecule that contains the genetic information for our cellular biology. RNA comes in a trio of guises. There is messenger RNA (mRNA) that is produced from DNA and contains the genetic instructions for forming proteins. Then there's ribosomal RNA (rRNA) that creates ribosomes vital for producing proteins, and finally transfer RNA (tRNA) that does the actual synthesizing of the proteins from mRNA. Because it is a simpler molecule than DNA, RNA is thought to have formed first, and thanks to its ability to carry genetic information and create other molecules, RNA has even been heralded as a possible main player in the story of the origin of life on Earth in a hypothesis colloquially known as "RNA world." In this scenario, the first single-celled lifeforms would have used RNA rather than DNA for self-replicating and copying their genetic information. Understanding how RNA formed has, however, been challenging. What prompted RNA's ingredients to come together just so and undergo the correct series of chemical reactions? On the face of it, the odds of RNA forming just by chance seem astronomical. So chemists look for pathways that could inevitably lead to the formation of molecules like RNA. One pathway is known as the six-step Discontinuous Synthesis Model (DSM). However, one of the stumbling blocks on this pathway is borate, which is a family of common compounds found in seawater. Borates are oxyanions; if ions are atoms or molecules that have a positive electrical charge, then anions have an overall negative electrical charge. Further, borates contain atoms of both boron and oxygen. The problem is that it had been thought that borates hinder some of the reactions on the chemical pathway to RNA. Now, a team of biochemists led by Yuta Hirakawa of Tohoku University in Japan and the Foundation for Applied Molecular Evolution in Florida say that chemists have been getting it wrong and that borates are actually beneficial to the formation of RNA. Source:Space.com @EverythingScience