The arrangement of axonemal microtubules in eukaryotic cilia and flagella is

Options

A. 9 + 2
B. 9 + 0
C. 18 + 2
D. 27 + 2

Answer

To solve the question regarding the arrangement of axonemal microtubules in eukaryotic cilia and flagella, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Cilia and Flagella**:
- Cilia and flagella are hair-like structures that extend from the surface of eukaryotic cells and are involved in movement. They share a common structural arrangement known as the axoneme.

2. **Identify the Components of the Axoneme**:
- The axoneme consists of microtubules arranged in a specific pattern. It is crucial to recognize that microtubules are protein filaments made of tubulin.

3. **Examine the Arrangement of Microtubules**:
- In eukaryotic cilia and flagella, the arrangement of microtubules is typically described as a "9 + 2" structure. This means there are 9 peripheral microtubule doublets surrounding 2 central microtubules.

4. **Visualize the Structure**:
- If you visualize the axoneme, you will see that the 9 peripheral doublets are arranged in a circular pattern around the 2 central microtubules, resembling a cartwheel structure.

5. **Conclude the Answer**:
- Therefore, the arrangement of axonemal microtubules in eukaryotic cilia and flagella is referred to as the "9 + 2" arrangement.

### Final Answer:
The arrangement of axonemal microtubules in eukaryotic cilia and flagella is "9 + 2".

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