What is the longest phase of the cell cycle. Suggest a reason for this to be the case.
Before entering mitosis, the cell expands and duplicates its DNA.
The Correct Answer and Explanation is:
Correct Answer:
The longest phase of the cell cycle is interphase, specifically the S phase (synthesis phase) within interphase, is critical due to DNA replication, but interphase as a whole (which includes G₁, S, and G₂ phases) is considered the longest stage overall.
Explanation
The cell cycle is composed of four main stages: G₁ (Gap 1), S (Synthesis), G₂ (Gap 2), and M (Mitosis). Of these, interphase, which includes G₁, S, and G₂, is the longest phase of the cycle. Interphase can occupy up to 90% of the total time of the cell cycle. During this period, the cell grows, carries out normal metabolic activities, and prepares for cell division.
A major event during interphase is DNA replication, which occurs in the S phase. Accurate duplication of the entire genome is essential before a cell divides, ensuring that each daughter cell receives a complete set of chromosomes. This process is highly complex and involves the unwinding of the DNA double helix, synthesis of new strands, and error-checking mechanisms, which require time and energy.
The length of interphase, particularly the G₁ and S phases, allows the cell to carefully monitor internal and external conditions to determine if it is safe and beneficial to divide. During G₁, the cell grows and produces RNA and proteins. In G₂, the cell continues to grow and begins synthesizing proteins needed for mitosis. Several checkpoints during interphase ensure that damaged DNA is repaired before division proceeds, helping prevent mutations or cancer.
The reason interphase is the longest phase is because it is when all essential preparations for cell division occur, including cell growth, organelle duplication, and DNA replication. These processes must be carefully completed to maintain genomic stability and proper cell function. Rushing through interphase could lead to errors in the genetic material passed on to daughter cells, which may have serious consequences for an organism.
