In a cell cycle which phase takes the longest time to complete:
A. anaphase
B. interphase
C. prophase
D. telophase
The correct answer and explanation is :
The correct answer is B. interphase.
Explanation:
The cell cycle is a series of stages that a cell goes through as it prepares for division. It consists of two main stages: Interphase and Mitotic phase (M-phase). Interphase itself is divided into three phases: G1 phase, S phase, and G2 phase. The M-phase is further divided into mitosis (which includes prophase, metaphase, anaphase, and telophase) and cytokinesis.
Interphase is by far the longest phase of the cell cycle. It lasts for about 90% of the total cell cycle time, although the exact duration can vary depending on the type of cell and the organism. This phase is crucial because it prepares the cell for division.
- G1 phase (Gap 1): This phase is characterized by cell growth and the accumulation of the necessary resources for DNA replication. The cell also carries out its normal functions during G1.
- S phase (Synthesis): During this phase, DNA replication occurs, and the entire genome is duplicated, ensuring that both daughter cells will receive an identical set of chromosomes.
- G2 phase (Gap 2): In this phase, the cell continues to grow and produce proteins necessary for mitosis. The final preparations for cell division occur, including the duplication of organelles and the synthesis of microtubules that will form the mitotic spindle.
After interphase, the cell enters the M-phase, which includes prophase, metaphase, anaphase, telophase, and cytokinesis. Among these, the individual stages of mitosis are much shorter in duration compared to interphase.
- Prophase: The chromatin condenses into chromosomes, the nuclear envelope begins to break down, and the mitotic spindle starts to form.
- Metaphase: The chromosomes align in the center of the cell.
- Anaphase: The sister chromatids are pulled apart.
- Telophase: The nuclear envelope reforms around the separated chromatids.
Thus, interphase takes the longest time to complete because it is the phase during which most of the cell’s preparation for division occurs, including DNA replication and cellular growth. In contrast, the mitotic phases (anaphase, prophase, telophase) are significantly shorter.