The primary function of mRNA in protein synthesis is to convey genetic information from DNA to the ribosomes, where proteins are assembled. Messenger RNA is synthesized during transcription, where DNA is decoded into a complementary RNA strand. This mRNA carries the necessary genetic code in the form of codons, each specifying a particular amino acid. During translation, ribosomes read the mRNA sequence and, with the help of transfer RNA (tRNA), assemble amino acids into a polypeptide chain, eventually forming proteins essential for cellular functions.