Final answer:
During DNA replication, transcription copies a DNA sequence into a related molecule called mRNA, which is crucial for protein synthesis.
Step-by-step explanation:
During DNA replication, to produce protein, a process called transcription copies the sequence of part of one strand of a DNA molecule into a related molecule, known as mRNA (messenger RNA). This process of transcription involves creating a complementary RNA strand from a DNA template, a step crucial for protein synthesis. Then, through the process known as translation, the mRNA molecule serves as a template to guide the synthesis of a protein with a specific sequence of amino acids encoded by the gene.