Chromosomes at anaphase are of various shapes depending upon position of centromere. It is J shaped when centromere is

Options

A. middle
B. top
C. subterminal
D. near centre

Answer

To determine the shape of chromosomes at anaphase based on the position of the centromere, follow these steps:

### Step-by-Step Solution:

1. **Understand Chromosome Structure**:
- Chromosomes consist of two sister chromatids joined at a region called the centromere. The position of the centromere affects the shape of the chromosome during anaphase.

2. **Identify Types of Chromosomes Based on Centromere Position**:
- **Metacentric Chromosomes**: Centromere is located in the middle, resulting in a V-shaped structure.
- **Submetacentric Chromosomes**: Centromere is slightly off-center, leading to one short arm and one long arm, giving an L-shaped appearance.
- **Acrocentric Chromosomes**: Centromere is located near one end, resulting in a J-shaped structure.
- **Telocentric Chromosomes**: Centromere is at the very end, resulting in an I-shaped structure.

3. **Determine the Shape of the Chromosome in Question**:
- The question asks for the shape of the chromosome when the centromere is in a specific position. The J-shaped chromosome corresponds to the acrocentric type, where the centromere is near one end.

4. **Conclude the Position of the Centromere for J-shaped Chromosomes**:
- Since J-shaped chromosomes are acrocentric, the centromere must be located near the tip of the chromosome, but not at the very end. Therefore, the correct position of the centromere for a J-shaped chromosome is **subterminal**.

5. **Final Answer**:
- The J-shaped chromosome occurs when the centromere is in the **subterminal position**.