What is the longest phase in the cell cycle?

Interphase is indeed the longest phase of the cell cycle, lasting much longer than the other phases such as mitosis, cytokinesis, and prophase. Interphase encompasses three sub-phases: G1 (gap 1 phase), S (synthesis phase), and G2 (gap 2 phase). During interphase, the cell grows, duplicates its DNA, and prepares for mitosis. This phase accounts for about 90% of the total cell cycle duration in a typical dividing cell.

During interphase, the cell undergoes significant metabolic activities and prepares essential components for cell division, making it vital for ensuring that the daughter cells receive identical and complete sets of genetic material. This extensive preparation necessitates a longer duration compared to the relatively rapid processes of cell division seen in mitosis and cytokinesis.

Mitosis and cytokinesis, which involve actual cell division, occur in a more defined timeframe. Prophase, as a part of mitosis, is one of the stages of cell division within that timeframe as well. Hence, interphase stands out as the phase that significantly contributes to the overall duration of the cell cycle.