Protein synthesis can be compared to building a doghouse. Sondra wanted to build a doghouse and found a book in the reference section in the local library. She copied the pages of directions using wood and nails to make the doghouse. Taking the directions to her workbench, Sondra used a hammer to put nails into their correct positions in the wood to make the doghouse. In the story, what genetic structure would be analogous to the copies from the reference book?