The molecule that carries an amino acid to the site of protein synthesis is called transfer RNA (tRNA).

Here's why:

* Structure: tRNA molecules have a unique cloverleaf shape. One end of the tRNA carries a specific amino acid, while the other end has an anticodon that recognizes a specific codon on the messenger RNA (mRNA).

* Function: During protein synthesis, tRNA molecules act like "taxi cabs" that pick up amino acids from the cytoplasm and deliver them to the ribosome, where they are added to the growing polypeptide chain according to the instructions in the mRNA.

Let me know if you have any more questions!