RNA polymerase is an essential enzyme found in all living cells. Its primary role is to synthesize RNA from a DNA template during a process called transcription. This means that RNA polymerase reads the DNA sequence and creates a complementary strand of RNA, which is crucial for producing proteins that carry out various functions in the cell. There are different types of RNA polymerases, each responsible for synthesizing different types of RNA. For example, RNA polymerase II specifically makes messenger RNA (mRNA), which serves as a blueprint for protein synthesis. Without RNA polymerase, cells would not be able to express genes and produce the proteins necessary for life.