Final answer:
The RNA world hypothesis suggests that RNA was the original molecule essential for early life, combining genetic storage and catalytic functions, which paved the way for the evolution of DNA and proteins.
Step-by-step explanation:
The RNA world hypothesis posits that RNA was the first, self-replicating molecule that led to the advent of life. According to this hypothesis, RNA could encode genetic instructions and catalyze chemical reactions, effectively bridging the gap between genetic information and catalytic function. During Earth's early history, RNA performed the roles of both genetic material and catalyst, which are now filled by DNA and proteins respectively.
The complexity of the RNA world eventually gave rise to DNA, a more stable genetic material, and proteins, which are more efficient catalysts. The transition from RNA as the prime molecule to a world where DNA and proteins dominate is believed to have been gradual, with the advent of ribonucleoprotein (RNP) complexes, enabling the formation and stabilization of proteins, which then took over the majority of the catalytic and structural functions of cells.
Evidence supporting the RNA world includes the existence of ribozymes and mechanisms such as ribonucleoprotein structures that are reminiscent of an ancient, RNA-centric biochemistry. Additionally, modern molecular biology techniques such as in vitro evolution studies with ribozymes provide experimental support for the hypothesis.