Final answer:
The element found in both prokaryotes and eukaryotes is promoters, particularly the TATA box, which facilitates transcription initiation. This sequence enables unwinding of DNA for RNA Polymerase binding in both types of cells.
Step-by-step explanation:
The element found in both prokaryotes and eukaryotes is promoters. Both prokaryotic and eukaryotic promoters contain sequences necessary for the initiation of transcription. Specifically, the TATA box is a shared feature, being an A-T rich sequence that helps to locally unwind DNA during the transcription process.
In prokaryotes, this sequence is similar to the -10 sequence, while in eukaryotes, it is generally located at -25 to -35 bases relative to the initiation site. This allows the necessary access for RNA Polymerase to bind and begin copying the DNA into RNA.
While other elements like introns, 5'-capping, and RNA splicing are associated with eukaryotic processes, it's important to note that the ribosome, the messenger molecule responsible for protein synthesis, is also found in both eukaryotic and prokaryotic cells.