Theories of Life

This week we spent a lot of time discussing  the origins of life as we know it. The two main theories are metabolism first and replication (RNA world). No one knows which theory is correct and there is a lot of proof to disprove both sides but no one really knows and new science is coming out all the time.

Metabolism first is the theory that electrons extracted from reduced organic molecules from hydrothermal vents. Then iron sulfide surrounds the organic molecules that are produced and electrons break off with temperature change. Over time tini life molecules collected and come together to form life. A major aspect of this theory is the Kreb cycle. The Kreb cycle is when electrons are extracted from reduced organic molecules. So pretty much hydrothermal vents = life. The arguments against metabolism first is that there hasn’t been enough testing because it’s a relatively new idea and also the big question that has yet to be answered is how can there be life with no DNA first?

The second and eldest theory is that there was first organic molecules and then it formed ribonucleotides which then replicated into long chain polymers then RNA and then the RNA got faster to form DNA. A DNA molecules primary function is replication and proteins carry out a variety of chemical reactions required for metabolism. Some theories predict that we came from space because these chemical reactions can happen on asteroids and comets which used to land on earth. SO the building blocks for life could have come from space. SOme arguments against this idea are that these molecules are unstable and may break down before they can form into nucleotides. It is, however, possible for nucleotides to form without first having sugar and a base. It is possible for nucleotides to link together to form RNA. But again, they are unstable.

Personally I don’t believe either. Both have been pretty much debunked. The only reason that metabolism first doesn’t have more evidence against it is because it’s the newest theory so there has been less time to disprove it. It would be pretty cool if we came from space though.