Question

Where do free-floating nucleotides come from?

Answer 1

The liver is the major organ of synthesis of all four nucleotides. Synthesis of pyrimidines (and purines follows two different pathways. Pyrimidines (C, T, U) are synthesized first from aspartate and carbamoyl-phosphate in the cytoplasm (...). Purines (A, G), however, are first synthesized from the sugar template onto which the ring synthesis occurs. For reference, the syntheses of the purine and pyrimidine nucleotides are carried out by several enzymes in the cytoplasm of the cell, not within a specific organelle. Nucleotides undergo breakdown such that useful parts can be reused in synthesis reactions to create new nucleotides.
(c) wikipedia

Answer 2

Thank you

Answer 3

Thank you for citing your source.