What step in protein synthesis means to copy into a complementary sequence of codons in a strand of RNA?

In the process of protein synthesis, transcription is the step where the genetic information encoded in DNA is copied into a complementary RNA sequence. During transcription, the DNA unwinds, and one of its strands serves as a template for synthesizing messenger RNA (mRNA). The enzyme RNA polymerase reads the DNA template and constructs an RNA strand by matching the DNA bases with their complementary RNA bases—adenine pairs with uracil instead of thymine, while cytosine pairs with guanine.

This process is essential because it allows the information in the DNA, which remains in the nucleus, to be translated into proteins, which occur in the cytoplasm. The mRNA then carries this coded information to the ribosomes, where translation takes place. Thus, understanding transcription is critical for grasping how genetic information is expressed and ultimately leads to protein synthesis.