What does mRNA (messenger RNA) primarily do?

Messenger RNA (mRNA) primarily carries the genetic code from DNA to the ribosomes, where proteins are synthesized. This process begins in the nucleus, where DNA is transcribed into mRNA. The mRNA then travels from the nucleus to the cytoplasm, specifically to the ribosomes, which are the cellular machinery responsible for translating the mRNA's sequence into a protein. Thus, the primary role of mRNA is to serve as a template that conveys the genetic instructions for building proteins, reflecting the information encoded in the DNA.

While mRNA does play an important role in facilitating the translation of proteins, this function is secondary to its main role of carrying the genetic code. Moreover, mRNA does not replicate DNA strands, as that process is carried out by enzymes such as DNA polymerase during DNA replication. It is also not directly responsible for regulating gene expression, although mRNA levels can be a factor in gene expression dynamics. However, the fundamental concept remains that mRNA’s primary role is to act as the messenger that transmits genetic information from DNA to the site of protein synthesis.