While the fact that life on Earth has emerged and flourished is abundantly clear, the mechanisms behind the origin of life still evade scientists. Where did the proteins and genetic information that have given rise to life originate? Which came first: the proteins or the genetic information? How did a self-replicating chemical system -- the beginnings of genetic history according to Dr. Francis Crick -- initiate? How did "left-handed" amino acids and "right-handed" sugars and nucleotides connect to form RNA and DNA despite the fact that "left-handed" nucleotides normally block "right-handed" nucleotides from linking together?
While the answers to these questions may still be just outside our grasps, four recent breakthroughs by scientists have given hope for insight into these prebiotic puzzles.
- Researcher Jack W. Szostak has shown that simple fatty acids, like those that existed in a primitive earth, will form double-layered spheres similar to cell membranes. As this protocell incorporates more fatty acids, it will eventually divide, much like normal cell division. Furthermore, Dr. Szostak and his colleagues have found that small molecules could pass through this protocell membrane. If these tiny molecules form with other like molecules into a larger molecule, they cannot leave the cell. This could explain how larger molecules, including DNA, formed inside early protocells.
- Chemist John Sutherland and his colleagues Matthew W. Powner and Béatrice Gerland have discovered a "recipe" for nucleotides -- the building blocks of RNA and DNA -- using base components assumed to have existed on a primitive earth. Their breakthrough was the realization that the base and the sugar of a nucleotide did not have to form separately but instead could have built up as a single unit.
- Dr. Gerald F. Joyce of the Scripps Research Institute has developed molecules that are "immortal," meaning they can pass on their information indefinitely. So far, Dr. Joyce has developed two RNA molecules that promote each other's synthesis from the four kinds of RNA nucleotides. Dr. Sutherland believes it will only be a matter of time before Dr. Joyce recreates full self-replication of RNA species.
- Finally, researchers like Donna Blackmond of Imperial College London are nearing a solution for the "handedness" problem of nucleotides. While normally "left-handed" nucleotides inhibit the linking of "right-handed" ones (thanks to a problem known as "original syn"), when given the right cycle of freezing and melting, a mixture of left and right nucleotides can be converted to just one type, which could then freely connect.
To read more about these four breakthroughs and how they can help us better understand the processes that led to the origin of life, check out the full article "New Glimpses of Life's Puzzling Origins" from The New York Times' website. You can read more about Dr. Sutherland's reasearch on the origin of nucleotides in our earlier post "Chemist Shows How RNA May Have Formed." For more on the origin of life, check out "Isn't the Origin of Life Highly Improbable?" in our Questions section at www.biologos.org.