During protein synthesis, messenger RNA (mRNA) carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm.

Here's a breakdown of what mRNA does:

* Transcription: mRNA is created in the nucleus by copying the sequence of a gene from DNA.

* Translation: mRNA travels to the ribosome in the cytoplasm, where it serves as a template for protein synthesis. The ribosome reads the mRNA sequence in codons (sets of three nucleotides) and uses this information to assemble a chain of amino acids, forming a protein.

So, in short, mRNA acts as a messenger between DNA and the ribosome, carrying the genetic instructions for building proteins.