What is the first step of DNA replication?

• A. The joining of Okazaki fragments by DNA ligase
• B. The unwinding of the DNA double helix by helicase
• C. The elongation of the new DNA strand by DNA polymerase
• D. The synthesis of RNA primers by primase

Answer: (B)

Verified step by step guidance

1. Understand that DNA replication is a process by which a cell duplicates its DNA before cell division.
2. Recognize that the first step in DNA replication involves the unwinding of the DNA double helix.
3. Identify the enzyme responsible for unwinding the DNA double helix, which is helicase.
4. Learn that helicase breaks the hydrogen bonds between the complementary bases of the DNA strands, separating them.
5. Note that this unwinding creates a replication fork, which is the site where the replication process will proceed.