What is the process of making identical copies of DNA before cell division?

• A. DNA Replication
• B. Transcription
• C. Translation
• D. Mutation

Answer: (A)

DNA replication is the process by which a cell copies its DNA before division. The double helix is opened at origins by helicase, creating replication forks. Each original strand serves as a template for a new complementary strand, so the two new DNA molecules are identical to the original. Primase lays down RNA primers to start synthesis, and DNA polymerase adds nucleotides in the 5′ to 3′ direction, pairing A with T and G with C. On the leading strand, synthesis is continuous; on the lagging strand, it proceeds in short Okazaki fragments that are later sealed by ligase. The result is two DNA molecules that are semi-conservative, each with one old strand and one new strand. This replication happens during the S phase of the cell cycle, ensuring each daughter cell inherits an exact copy. Transcription and translation are different processes (making RNA from DNA, and protein from RNA, respectively), and mutations are changes in the DNA sequence.