Final answer:
Poly(A) polymerase uses adenosine monophosphate (AMP) to add adenine bases to the 3' end of mRNA, forming a protective poly-A tail that aids in mRNA stability, transportation, and processing signaling.
Step-by-step explanation:
Poly(A) polymerase uses adenosine monophosphate (AMP) to add adenines and create the poly-A tail at the 3' end of an mRNA molecule. This enzyme is crucial for polyadenylation, which is a post-transcriptional modification. Polyadenylation involves the addition of a sequence of adenine nucleotides following transcription termination. The poly-A tail conferred by poly(A) polymerase serves multiple functions: it protects the mRNA from degradation, facilitates mRNA export to the cytoplasm, and signals the completion of mRNA processing. Poly(A) polymerase specifically recognizes the AAUAAA sequence near the 3' end of the mRNA and catalyzes the addition of AMP residues, often up to 200 or more.