What is the longest stage of the cell cycle called?

The longest stage of the cell cycle is called the interphase. Interphase is often considered to be the "resting" or "growth" phase of the cell cycle, but in reality, it is a very active period where many important cellular processes occur.

During interphase, the cell grows in size and synthesizes proteins and organelles necessary for cell division. It can be further divided into three sub-phases:

1. G1 (Gap 1) phase: This is the first phase of interphase, where the cell grows in size and carries out normal cellular functions. It also decides whether the cell should divide or enter a non-dividing state called the G0 phase.

2. S (Synthesis) phase: In this phase, the DNA replication takes place. Each chromosome is duplicated, resulting in the formation of two identical sister chromatids held together at a structure called the centromere.

3. G2 (Gap 2) phase: In the G2 phase, the cell continues to grow and prepares for cell division by producing necessary proteins and organelles. It also checks the accuracy of DNA replication and repairs any errors.

Overall, interphase is crucial for the cell's growth, development, and preparation for division. It typically accounts for about 90% of the cell cycle duration, while the remaining 10% is divided between the mitosis and cytokinesis stages.