Number of chromatids per chromosome at metaphase is

Options

A. two each in mitosis and meiosis
B. two in mitosis and one in meiosis
C. two in mitosis and four meiosis
D. one in mitosis and two in meiosis

Explanation

To determine the number of chromatids per chromosome at metaphase, we need to understand the structure of chromosomes during this specific phase of cell division, both in mitosis and meiosis.

### Step-by-Step Solution:

1. **Understanding Chromatids**:
- A chromatid is one half of a duplicated chromosome. After DNA replication, each chromosome consists of two identical sister chromatids.

2. **Metaphase Overview**:
- Metaphase is a stage in both mitosis and meiosis where chromosomes align at the metaphase plate (the equatorial plane of the cell).

3. **Chromosome Structure at Metaphase**:
- During metaphase, each chromosome is made up of two sister chromatids. This is true for both mitosis and meiosis.

4. **Mitosis**:
- In mitosis, the chromosomes are duplicated before the cell divides, resulting in two sister chromatids per chromosome at metaphase.

5. **Meiosis**:
- In meiosis, during metaphase I, homologous chromosomes (each consisting of two sister chromatids) align at the metaphase plate. In metaphase II, the same is true; each chromosome still consists of two sister chromatids.

6. **Conclusion**:
- Therefore, at metaphase, each chromosome has 2 chromatids in both mitosis and meiosis.

### Final Answer:
The number of chromatids per chromosome at metaphase is **2 each in mitosis and meiosis**.