Cyclin is required for cell cycle. Which other molecule is essential for completion of cell cycle ?

Options

A. C CK
B. CKC
C. CDK
D. CKD

Answer

**Step-by-Step Text Solution:**

1. **Understanding Cyclin**: Cyclins are proteins that play a crucial role in regulating the cell cycle. They are involved in various phases of the cell cycle, ensuring that the cell progresses through different stages at the right time.

2. **Identifying the Partner Molecule**: Cyclins work in conjunction with another type of molecule known as cyclin-dependent kinases (CDKs). These kinases are enzymes that require cyclins to be activated.

3. **Function of CDKs**: CDKs, when activated by their corresponding cyclins, phosphorylate target proteins that are necessary for the progression of the cell cycle. This phosphorylation is essential for the cell to move from one phase of the cycle to the next.

4. **Phases of the Cell Cycle**: The cell cycle consists of several phases: G1 phase, S phase, G2 phase, and M phase. Each phase requires specific cyclins and CDKs to ensure proper progression:
- **G1 Phase**: Cyclins D and E are required, with CDKs 4, 2, and 6.
- **S Phase**: Cyclins A and E are required, with CDKs 2 and 1.
- **G2 Phase**: Cyclin A is required, with CDK 2.
- **M Phase**: Cyclin B is required, with CDK 1.
- **G0 Phase**: Cyclin C is required, with CDK 3.

5. **Conclusion**: Therefore, in addition to cyclins, cyclin-dependent kinases (CDKs) are essential for the completion of the cell cycle.

**Final Answer**: CDK (Cyclin-dependent kinases) is essential for the completion of the cell cycle.

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