The Three Phases of Interphase: G1, S, and G2 – A Comprehensive Guide to Cell Cycle Growth and DNA Synthesis

3 parts of interphase

Interphase is the longest phase of the cell cycle and is divided into three distinct parts: G1 phase, S phase, and G2 phase

Interphase is the longest phase of the cell cycle and is divided into three distinct parts: G1 phase, S phase, and G2 phase.

1. G1 Phase (Gap 1 Phase): This is the first phase of interphase, where the cell undergoes growth and prepares for DNA synthesis. During G1 phase, the cell increases in size, produces proteins and organelles, and carries out normal cellular functions. This phase is also known as the “first gap” phase as it represents the time between the end of cell division in the previous cycle and the initiation of DNA replication.

2. S Phase (Synthesis Phase): The S phase follows the G1 phase and represents the period of DNA synthesis. During this phase, the cell replicates its entire genome to produce two copies of each chromosome. Each chromosome is unraveled, and its DNA is duplicated by the action of enzymes and proteins involved in DNA replication. As a result, by the end of the S phase, the cell contains double the amount of DNA than it had at the beginning.

3. G2 Phase (Gap 2 Phase): After DNA synthesis in the S phase, the cell enters the G2 phase. During this stage, the cell continues to grow and prepare for cell division. The G2 phase is also known as the “second gap” phase as it occurs after DNA replication but before the cell enters the actual process of cell division (mitosis or meiosis). The cell synthesizes additional proteins and organelles required for cell division, and it undergoes various checkpoints to ensure that DNA replication has occurred accurately.

Together, the three parts of interphase, G1, S, and G2, ensure proper growth and preparation of the cell before entering the next phase of the cell cycle, which is either mitosis or meiosis.

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