**Question:** In conversion of DNA to RNA, enzyme required:

A. DNA polymerase
B. RNase
C. DNA ligase
D. DNA primase

**Core Concept:** Transcription is the process by which genetic information from DNA is copied into RNA. In prokaryotes, this process is initiated by the enzyme DNA primase, which synthesizes short RNA primers that serve as starting points for DNA polymerase. DNA polymerase is responsible for synthesizing the RNA strand complementary to the DNA template strand. RNase is an enzyme that breaks down RNA molecules. DNA ligase is an enzyme involved in DNA repair and joining of DNA fragments, not transcription.

**Why the Correct Answer is Right:** The correct answer, DNA polymerase, is essential for the synthesis of RNA complementary to the DNA template strand. DNA primase, on the other hand, is responsible for synthesizing short RNA primers that initiate DNA replication, not transcription. RNase is an RNA-degrading enzyme, meaning it breaks down RNA molecules and is not involved in transcription. DNA ligase is involved in DNA repair and joining of DNA fragments, not transcription.

**Why Each Wrong Option is Incorrect:** Option A (DNA polymerase) is correct because it synthesizes the RNA strand complementary to the DNA template strand, enabling the transcription process to proceed. Option B (RNase) is incorrect because it is an RNA-degrading enzyme and not involved in transcription. Option C (DNA ligase) is incorrect because it is involved in DNA repair and joining of DNA fragments, not transcription. Option D (DNA primase) is incorrect because it synthesizes RNA primers for DNA replication, not transcription.

**Clinical Pearl:** Understanding the role of different enzymes in transcription and replication is crucial for understanding genetic processes and their clinical implications in diseases like cancer, where mutations in these enzymes can lead to abnormal DNA replication and transcription processes.