Explanation of Porins and the Odd One Out

Porins are integral membrane proteins that form channels in the outer membranes of Gram-negative bacteria, mitochondria, and plastids. These channels allow small molecules to pass through the membrane, including nutrients, ions, and waste products. Porins are also involved in the regulation of water homeostasis and play a role in bacterial virulence.

Option A - Not Associated with the Inner Membrane of Plastid

Plastids are organelles found in plant cells that are involved in photosynthesis and other metabolic processes. They have two membranes, the inner and outer membranes. Porins are found in the outer membrane of plastids, but not in the inner membrane. Therefore, Option A is not the odd one out with respect to porins.

Option B - Associated with the Outer Membrane of Mitochondria

Mitochondria are organelles found in eukaryotic cells that are involved in energy production through cellular respiration. They have two membranes, the inner and outer membranes. Porins are found in the outer membrane of mitochondria, but not in the inner membrane. Therefore, Option B is not the odd one out with respect to porins.

Option C - Found in Outer Membrane of Gram-Positive Bacteria

Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, which protects them from environmental stress. They do not have an outer membrane like Gram-negative bacteria, but they still have porins in their cell membranes. Porins in Gram-positive bacteria are found in the plasma membrane, which is the only membrane they have. Therefore, Option C is not the odd one out with respect to porins.

Option D - Allow Movement of Low Molecular Weight Hydrophilic Substances

All porins allow the movement of low molecular weight hydrophilic substances through the membrane. This is their primary function, and it is a characteristic shared by all porins. Therefore, Option D is not the odd one out with respect to porins.

Conclusion

After analyzing all the options, we can conclude that there is no odd one out with respect to porins. All the options are correct and relate to porins in some way.

The answer is C. . because porins are found in outer membrane of mitochondria and plastid and bacteria... but gram positive bacteria does not have outer membrane..so they do not have porins