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 in meiosis
D. One in mitosis and two in meiosis

Explanation

To determine the number of chromatids per chromosome at metaphase, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Chromosomes**:
- A chromosome can exist in two forms: a monad (single chromatid) and a dyad (two sister chromatids).

2. **Chromatid Duplication**:
- During the S phase of the cell cycle, each chromosome is duplicated. This means that each chromosome, which initially exists as a single chromatid (monad), is replicated to form two identical sister chromatids (dyad).

3. **Metaphase Stage**:
- At metaphase, chromosomes are aligned at the equatorial plane of the cell. Each chromosome is in the form of a dyad, meaning it consists of two sister chromatids.

4. **Counting Chromatids**:
- Regardless of whether the cell is undergoing mitosis or meiosis, each chromosome at metaphase consists of two chromatids. Therefore, for each chromosome, the number of chromatids is 2.

5. **Conclusion**:
- The answer to the question of how many chromatids are present per chromosome at metaphase is 2.

### Final Answer:
The number of chromatids per chromosome at metaphase is **2**.

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