Here's how it works:

1. Transcription: DNA in the nucleus is transcribed into mRNA. This mRNA molecule carries the genetic code from the DNA to the ribosomes, which are the protein-making machinery of the cell.

2. Translation: At the ribosome, the mRNA molecule is read three bases (codons) at a time. Each codon corresponds to a specific amino acid.

3. Amino Acid Delivery: Transfer RNA (tRNA) molecules, which are also involved in protein synthesis, bring the corresponding amino acids to the ribosome based on the codons in the mRNA.

4. Polypeptide Chain Formation: The ribosome links these amino acids together in the order specified by the mRNA, forming a polypeptide chain.

5. Folding: The polypeptide chain then folds into a specific three-dimensional shape, creating the functional protein.

So, while tRNA and rRNA also play crucial roles in protein synthesis, mRNA is the molecule that actually carries the blueprint for protein construction.