Second check point of cell cycle lies between

Options

A. `G_1and S` phase
B. `S and S_2` Phase
C. `G_2 and M` phase
D. `M and G_1` Phase

Answer

To determine the second checkpoint of the cell cycle, we need to analyze the phases of the cell cycle and their respective checkpoints. Here’s a step-by-step solution:

### Step 1: Understand the Cell Cycle Phases
The cell cycle consists of several phases:
- **G1 Phase (Gap 1)**: The cell grows and synthesizes proteins necessary for DNA replication.
- **S Phase (Synthesis)**: DNA replication occurs, resulting in the duplication of chromosomes.
- **G2 Phase (Gap 2)**: The cell continues to grow and prepares for mitosis.
- **M Phase (Mitosis)**: The cell divides into two daughter cells.

### Step 2: Identify the Checkpoints
There are several checkpoints in the cell cycle:
1. **G1 Checkpoint**: Checks for cell size, DNA integrity, and environmental conditions before entering the S phase.
2. **G2 Checkpoint**: Checks for DNA damage and ensures that DNA replication has been completed accurately before entering mitosis (M phase).
3. **M Checkpoint**: Ensures that all chromosomes are properly attached to the spindle apparatus before the cell divides.

### Step 3: Determine the Second Checkpoint
From the information above, we can see that:
- The first checkpoint occurs between G1 and S phases.
- The second checkpoint occurs between G2 and M phases.

### Conclusion
Therefore, the second checkpoint of the cell cycle lies between the **G2 and M phases**.

### Final Answer
The correct option is: **G2 and M phase**.

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