Question

Biologists believe that the current DNA to RNA to Protein system is the result of a long period of evolution because
A)The transcription of DNA to mRNA and translation of mRNA into proteins consists of many steps.
B)DNA replication is complicated but relatively error-free and the current system is very complex and precise.
C)Evidence indicates that RNA preceded DNA as the genetic material.
D)All of the above.

Answer 1

The theory of the RNA universe suggests that molecules of self-replicating ribonucleic acid (RNA) are precursors to all modern life on Earth. While RNA-based life may not have been the first life to exist, it is widely agreed that current life on Earth comes from an RNA universe.

Complete answer:
RNA stores genetic information such as DNA and, like an enzyme protein, catalyzes chemical reactions. Therefore, it may have been a significant phase in the evolution of cell life. Eventually, the RNA universe would have been replaced by today's DNA, RNA and protein world, presumably by an intermediate stage of ribonucleoprotein enzymes such as ribosomes and ribozymes, since proteins large enough to self-fold and have useful activities would have arisen only after the peptide ligation catalyst or amino acid polymerization of RNA was usable.

Because of its improved stability, DNA is believed to have taken over the role of data storage, while proteins have substituted RNA's role in advanced biocatalysis by a larger variety of monomers (amino acids).

Many separate lines of evidence support the RNA world hypothesis, such as the findings that RNA is central to the translation mechanism and that small RNAs can catalyze the whole chemical group and the transfers of information essential for life. The ribosome arrangement was dubbed the "smoking gun," when it revealed that the ribosome is a ribozyme with a central RNA center and no side amino acid chains within 18 angstroms of the active site where the formation of peptide bonds is catalyzed.

Hence, the correct answer is option (C)

Note: Most biologists claim RNA was the first genetic material since the presence of ribozymes means that RNA may have been used by early cells to catalyze chemical reactions and transfer data. Biologists also conclude that the present DNA RNA protein system is the product of a long evolutionary cycle since data suggests that DNA as the genetic material preceded RNA.