Final answer:
RNA nucleotides, made up of ribose, a phosphate group, and nitrogenous bases adenine, guanine, cytosine, and uracil, come from within cells or dietary sources. The initial formation of these nucleotides in the prebiotic world is a complex subject, likely involving simpler compounds gradually forming more complex RNA structures.
Step-by-step explanation:
The nucleotides found in RNA are derived from the breakdown and reassembly of existing nucleic acid polymers within the cell or from the dietary intake of nucleotides, which are then absorbed and used by the cell. The building blocks of RNA nucleotides consist of three components: a five-carbon sugar called ribose, a nitrogenous base, and a phosphate group. The nitrogenous bases in RNA are adenine, guanine, cytosine, and uracil, with uracil replacing thymine found in DNA.
In the primordial world, the origin of nucleotides and the RNA they form is subject to much scientific conjecture, notably the RNA World hypothesis. However, the synthesis of RNA's building blocks under prebiotic conditions remains a complex challenge due to the intricate nature of these molecules and the specialized reactions required to assemble them, often necessitating catalysis by enzymes.
These enzymes would already exist within developed cells or protocells, suggesting that simpler organic compounds might have gradually given rise to more complex nucleotides and eventually RNA.