Question

The replication of DNA takes place during which phase

(I) Mitosis
(II) G${}_1$phase
(III) S phase

• A. I only
• B. II only
• C. III only
• D. I and III only
• E. I, II and III

Answer 1

The correct option is C III only

DNA replication in most eukaryotic cells occurs, only during a specific part of the cell division cycle called the DNA synthesis phase or S phase. In a mammalian cell, the S phase typically lasts for about 8 hours. In simpler eukaryotic cells such as yeasts, the S phase can be as short as 40 minutes. By its end, each chromosome has been replicated to produce two complete copies, which remain joined together at their centromeres until the M phase (mitosis), which soon follows.