What does mRNA do during protein synthesis?

mRNA, or messenger RNA, plays a crucial role in protein synthesis by carrying the genetic instructions from the DNA in the nucleus to the ribosomes, where proteins are assembled. During the process of transcription, the DNA sequence of a gene is transcribed into a complementary strand of mRNA. This mRNA then travels out of the nucleus into the cytoplasm, where it interacts with ribosomes to guide the synthesis of proteins based on the encoded instructions. This role as a messenger is essential for translating the genetic code into functional proteins, as the ribosomes read the sequence of nucleotides in the mRNA to assemble amino acids in the correct order.

The other options, while related to the broader context of protein synthesis, do not accurately describe the primary function of mRNA. Reading the DNA code and decoding amino acids pertain to different aspects of gene expression and translation, whereas transferring amino acids refers more specifically to the function of tRNA (transfer RNA), which brings the appropriate amino acids to the ribosome, rather than mRNA.