Question

Which is evidence that RNA probably evolved before DNA and proteins to serve important functions in the prebiotic world?

1) RNA is involved in various cellular processes such as protein synthesis
2) RNA can act as a catalyst, facilitating chemical reactions
3) RNA can store genetic information
4) RNA is found in all living organisms

Answer 1

Evidence suggesting that RNA probably evolved before DNA and proteins includes:

RNA can act as a catalyst, facilitating chemical reactions. Thus, the correct answer is option 2.

Step-by-step explanation:

RNA's ability to act as a catalyst, known as ribozyme activity, implies its functional role in facilitating chemical reactions without the need for protein enzymes (option 2). This characteristic suggests RNA's capacity to serve essential functions in the prebiotic world, potentially preceding the evolution of proteins. Ribozymes, formed from RNA molecules, can catalyze various biochemical reactions, indicating RNA's capability to perform crucial roles in metabolic pathways and cellular processes without the involvement of proteins.

The ability of RNA to catalyze reactions provides insight into the primordial functions of early biomolecules. This catalytic activity suggests that RNA molecules, capable of both storing genetic information and catalyzing chemical reactions, could have served as early agents in the prebiotic environment. RNA's dual functionality as both an informational molecule and a catalyst supports the hypothesis of an RNA world preceding the emergence of DNA and proteins, indicating its fundamental role in early biological processes.

While RNA's involvement in cellular processes like protein synthesis and its ability to store genetic information are crucial aspects, the unique catalytic properties exhibited by ribozymes underscore RNA's potential as a primitive biopolymer that could have played a central role in the origin of life, providing key functions necessary for early biochemical processes before the emergence of more complex biological molecules like DNA and proteins.

Answer 2

RNA likely evolved before DNA and proteins, as suggested by the RNA world hypothesis, due to its ability to both store genetic information and act as a catalyst.

Step-by-step explanation:

The question pertains to the RNA world hypothesis, which posits that RNA likely evolved before DNA and proteins, playing a definitive role in the early stages of life on Earth.

The hypothesis is supported by the fact that RNA is multifunctional: it can store genetic information, act as a catalyst in chemical reactions similar to enzymes (e.g., ribozymes), and it plays an essential role in protein synthesis. Evidence for this includes the central dogma of molecular biology, which outlines the flow of genetic information from DNA to RNA to proteins, indicating RNA's crucial intermediary role.

Furthermore, RNA's versatility suggests a prebiotic world where RNA carried both the informational and functional burdens, resolving the 'chicken-and-egg' problem regarding which of the two systems, proteins or nucleic acids, appeared first.