In which tubulin protein is not present :-

Options

A. Plasma membrane
B. Cilia
C. Flagella
D. Microtubules

Answer

**Step-by-Step Solution:**

1. **Understanding Tubulin Protein**: Tubulin proteins are the building blocks of microtubules, which are structural components of the cytoskeleton in eukaryotic cells. They play a crucial role in maintaining cell shape, enabling cellular movement, and facilitating intracellular transport.

2. **Location of Tubulin Proteins**: Tubulin is primarily found in microtubules, which are present in various cellular structures, including cilia and flagella. These structures are essential for cell motility and movement.

3. **Arrangement in Cilia and Flagella**: In cilia and flagella, tubulin proteins are organized in a specific arrangement known as the "9 + 2" structure. This means there are 9 peripheral microtubule doublets surrounding 2 central microtubules.

4. **Identifying Where Tubulin is Not Present**: While tubulin is found in microtubules, it is important to identify where it is absent. The plasma membrane, also known as the cell membrane, does not contain tubulin proteins. Instead, the plasma membrane is primarily composed of a lipid bilayer, which includes phospholipids, integral proteins, peripheral proteins, and cholesterol.

5. **Conclusion**: Based on the information above, the correct answer to the question "In which tubulin protein is not present?" is the plasma membrane.

**Final Answer**: Tubulin protein is not present in the plasma membrane.

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