Now, when our mRNA combines with the ribosomes, what happens is our mRNA contains a three sequence nucleotide that is known as the codon. And the codon basically stands for some type of amino acid. Now, in order to bring that amino acid from some location inside our cytoplasm into the ribosome, we have to have some type of molecule. And the molecule that brings the amino acid into that ribosome is our transfer RNA. So transfer RNA are specialized molecules that collect the proper or appropriate amino acid and bring it into the ribosome where that amino acid is then attached to the growing polypeptide chain. So we see that all three of these different types of RNA molecules are synthesized inside the nucleus and they're all involved in the process in the synthesis of our proteins.