What is the first step in the process of gene expression?

The first step in the process of gene expression is transcription. During transcription, the DNA sequence of a gene is copied into messenger RNA (mRNA). This occurs in the nucleus of eukaryotic cells, where the enzyme RNA polymerase binds to the promoter region of the gene and synthesizes an RNA strand complementary to the DNA template.

Transcription is critical because it represents the initial phase where the genetic information encoded in DNA is converted into a form that can be translated into proteins, which are vital for cellular functions. Once the mRNA is synthesized, it undergoes several processing steps, such as 5' capping, polyadenylation, and splicing, before it can be translated into a protein. This makes transcription the foundational step in gene expression, setting the stage for the subsequent translation of the mRNA into a polypeptide chain, which ultimately folds into a functional protein.