Interdependence, Reflexivity, Fidelity, Impedance Matching, and the Evolution of Genetic Coding

The direct evolution of inherited genetic information coupled to encoded functional proteins is far more plausible than any scenario in which there was, as initial RNA, a world of ribozymes sophisticated enough to operate a genetic code.

“The direct evolution of inherited genetic information coupled to encoded functional proteins, as is observed in real-world molecular biology, is far more plausible than any scenario in which there was, as initial RNA, a world of ribozymes sophisticated enough to operate a genetic code [19].”

From bridge peptide, protozymes, then urzymes, and finally pre-aaRS and aaRS probably evolved.

“From bridge peptide, protozymes and then urzymes, and finally pre-aaRS and aaRS probably evolved [17,18,19,24].”

Protozymes retain about 40 percent of the activity of full-length aaRS even though they contain only about 10 percent as many amino acids.

“Protozymes retain about 40 percent of activity of the full-length of aaRS, even though they contain only about 10 percent as many amino acids.”

RNAs and proteins developed a symbiotic relationship to create ribosomes in the peptide/RNA world.

“RNAs and proteins developed a symbiotic relationship to create ribosomes in the peptide/RNA world [17,18,19].”

Urzymes retain about sixty percent of activity and have the same functional repertoire as full-length enzymes.

“Next came ‘urzymes’, which retain about sixty percent of activity and have the same functional repertoire as the full-length enzymes.”

The ribosome may have first originated in a peptide/RNA world, where both amino acids and a variety of enzymes were available.

“In recent times, the role of proteins in the origin of ribosomes is gaining currency, implying that the ribosome may have first originated in a peptide/RNA world, where both amino acids and a variety of enzymes were available [9,13,14,15,16,17,18,19,20,21,22,92].”

tRNAs carry two codes: the well-known anticodon and a second one in the acceptor stem.

“In this view, tRNAs carry two codes: the well-known anticodon and a second one in the acceptor stem (Figure 4E).”

In the peptide/RNA world, peptides should have been part of the very first steps in the establishment of the genetic code.

“In the peptide/RNA world, the peptides should have been part of the very first steps in the establishment of the genetic code [19,21,23].”

The nucleic acid sequence of the acceptor stem and the anticodon code for distinct physical properties of amino acids.

“These two codes are not arbitrary: the nucleic acid sequence of the acceptor stem and the anticodon code for distinct physical properties of amino acids.”