Final answer:
Transfer RNA (tRNA) is responsible for carrying amino acids to the ribosome, where they are added to the growing polypeptide chain during protein synthesis.
Step-by-step explanation:
The molecules called that carry amino acids to the ribosome are known as transfer RNA (tRNA). Each tRNA molecule is responsible for transporting a specific amino acid to the ribosome during protein synthesis. They function by matching their anticodon with the codons on the mRNA strand. This precise base pairing is crucial for the amino acids to be added in the correct order to the growing polypeptide chain. While the other types of RNA, mRNA and rRNA, are essential for the process, it is tRNA that directly delivers the amino acids.