In pachytene, each tetrad contains

Options

A. Two chromatids
B. One chromatids
C. Four chromatids
D. Three chromatids

Answer

To solve the question "In pachytene, each tetrad contains," we need to understand the context of the term "pachytene" and the structure of tetrads during this stage of meiosis.

### Step-by-Step Solution:

1. **Understanding Pachytene**:
- Pachytene is a stage in prophase I of meiosis. It follows the zygotene stage and precedes the diplotene stage.
- During this stage, homologous chromosomes pair up closely to form structures known as tetrads.

2. **Definition of Tetrad**:
- A tetrad consists of a pair of homologous chromosomes. Each homologous chromosome is made up of two sister chromatids.
- Therefore, when we refer to a tetrad, we are talking about two homologous chromosomes that have come together.

3. **Counting Chromatids**:
- Since each homologous chromosome has two sister chromatids, in a tetrad (which contains two homologous chromosomes), the total number of chromatids can be calculated as follows:
- Each of the two chromosomes has 2 chromatids:
- 2 chromatids (from the first chromosome) + 2 chromatids (from the second chromosome) = 4 chromatids in total.

4. **Conclusion**:
- Thus, in pachytene, each tetrad contains **4 chromatids**.

### Final Answer:
Each tetrad in pachytene contains **4 chromatids**.

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