Optometry Admission Test (OAT) Practice

During which phase of cell division does the cell double its organelles and cytoplasm?

1. G1 phase

2. S phase

3. G2 phase

4. M phase

The correct answer is: G1 phase

The G1 phase, or Gap 1 phase, plays a crucial role in the cell cycle, particularly in preparing the cell for DNA replication and subsequent division. During this phase, the cell undergoes significant growth, synthesizing proteins, producing organelles, and increasing its cytoplasmic volume. This preparation is essential because the cell needs to have sufficient resources and cellular components for two daughter cells after division. In contrast, the S phase is specifically dedicated to the replication of DNA. While the cell does continue to grow and some organelles may increase in number, the primary focus of the S phase is on duplicating the genetic material. The G2 phase, or Gap 2 phase, follows S phase and involves further growth and preparation for mitosis, including the synthesis of proteins necessary for mitosis but not as extensive a doubling of organelles and cytoplasm as in G1. The M phase, or mitosis, is when the cell actually divides and does not involve the doubling of organelles or cytoplasm. Therefore, the G1 phase is the most accurate answer, as it encompasses the critical initial steps of cellular growth and preparation for the later stages of division.