Florida Biology EOC Practice Test

Which enzyme bonds to the DNA molecule to initiate transcription?

1. DNA polymerase

2. Helicase

3. Ligase

4. RNA polymerase

The correct answer is: DNA polymerase

The process of transcription, where DNA is converted into RNA, is initiated by the enzyme RNA polymerase. This enzyme binds to specific regions of the DNA called promoters, which are located at the beginning of genes. Once bound, RNA polymerase unwinds the DNA double helix and synthesizes a complementary strand of RNA by adding ribonucleotides that are complementary to the DNA template strand. DNA polymerase, on the other hand, is primarily involved in DNA replication, where it synthesizes new DNA strands by adding deoxyribonucleotides to a growing DNA chain. Helicase plays a role in unwinding the DNA double helix during both replication and transcription, but it does not initiate the transcription process. Ligase is responsible for joining Okazaki fragments on the lagging strand during DNA replication and does not play a role in transcription at all. Thus, RNA polymerase is the correct enzyme that initiates transcription by binding to the DNA molecule.