During which phase is DNA replicated?

During which phase is DNA replicated?

• A. G1
• B. S phase (synthesis)
• C. G2
• D. M phase

Answer: (B)

DNA replication happens in the S phase, the synthesis phase, of the cell cycle. During this part of interphase, the cell copies its entire genome so that each chromosome consists of two sister chromatids by the time mitosis begins. This setup ensures that, when the cell divides, each daughter cell receives an identical set of genetic information. Other phases are about growth and preparation (G1 and G2) or actual division (M phase), not copying the DNA. Replication is semi-conservative, meaning each new DNA molecule has one old strand and one new strand.

DNA replication happens in the S phase, the synthesis phase, of the cell cycle. During this part of interphase, the cell copies its entire genome so that each chromosome consists of two sister chromatids by the time mitosis begins. This setup ensures that, when the cell divides, each daughter cell receives an identical set of genetic information. Other phases are about growth and preparation (G1 and G2) or actual division (M phase), not copying the DNA. Replication is semi-conservative, meaning each new DNA molecule has one old strand and one new strand.