Final answer:
Self-complementary sequences in RNA molecules allow them to undergo intramolecular base pairing, creating complex structures essential for function and interaction with other molecules, critical from early biological evolution to present-day cellular processes.
Step-by-step explanation:
The formation of self-complementary sequences within RNA molecules allows them to engage in intramolecular base pairing, leading to the creation of complex three-dimensional structures such as hairpins or cruciform shapes. This structure formation is essential for RNA to perform its various functions within the cell. RNA's ability to fold upon itself through hydrogen bonds between complementary base pairs enables it to take on specific shapes that are crucial for the interaction with other molecules, including those present in the prebiotic environment.
This structural versatility is significant in the RNA's role as a catalyst and in storing genetic information, a critical aspect of early biological evolution and current cellular processes. RNAs today are involved in key biochemical activities, some acting as autocatalysts and others forming part of essential structures like ribosomes.