Life from matter



In this process, imagine amino acids moving about randomly in a cell, possibly as the consequence of thermal (and quantum) noise. They bump randomly into the ribosome, which may be moving along a sequence of the genetic code written in messenger RNA sent from the cell nucleus (or in the case of bacteria, directly transcribed from DNA in the cell). This random motion shows us that no organized or coherent information is present in the unattached tRNAs that could cause something from the bottom up to emerge at a higher level. They are not carrying pre-determined information of where they belong in the protein. It is the information processing of the higher-level ribosome that is in control. As the ribosome moves along the string of mRNA, it reads the next three-letter codon and waits for a tRNA with a matching anti-codon to collide randomly. It might be some time (relatively) before the desired amino acid shows up.

In this thinking, the ribosome is an information-processing biological system that has emerged from the lower level of chemistry and physics to exert downward causation on the atomic and molecular components needed to make a protein.