Porins and aquaporins are presents in membranes of

Options

A. Plastid
B. Mitochondria
C. Bacteria
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Porins:**
- Porins are proteins that form hydrophilic channels in membranes.
- They are primarily found in the outer membranes of certain organelles and bacteria.
- Their function is to facilitate the passage of large molecules and small-sized proteins through the membrane by diffusion.

2. **Identifying Locations of Porins:**
- Porins are present in:
- **Plastids:** Double membrane-bound organelles found in plant cells.
- **Mitochondria:** Known as the powerhouse of the cell, they also have an outer membrane where porins are located.
- **Bacteria:** Many bacteria have porins in their outer membrane.

3. **Understanding Aquaporins:**
- Aquaporins are specialized proteins that form channels specifically for water transport.
- They allow the rapid diffusion of water molecules across cell membranes.

4. **Identifying Locations of Aquaporins:**
- Aquaporins are also found in:
- **Plastids:** They help in the regulation of water within these organelles.
- **Mitochondria:** They assist in water transport necessary for mitochondrial functions.
- **Bacteria:** Some bacteria also possess aquaporins for water transport.

5. **Conclusion:**
- Since both porins and aquaporins are present in the membranes of plastids, mitochondria, and bacteria, the correct answer to the question is "all of these."

**Final Answer:**
Porins and aquaporins are present in the membranes of plastids, mitochondria, bacteria, and therefore, the answer is "all of these."

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