Membrane Evolution—Inner Mitochondrial Membrane Resembles Which Structure? Based on composition and function, the inner mitochondrial membrane most closely resembles:

Introduction / Context:
The endosymbiotic theory proposes that mitochondria originated from an ancestral bacterium. The inner mitochondrial membrane retains bacterial-like features, consistent with this evolutionary origin, and distinct from typical eukaryotic membranes.

Given Data / Assumptions:

• Inner membrane houses the electron transport chain and ATP synthase.
• It contains cardiolipin and is highly protein-dense.
• It is relatively impermeable and relies on specific transporters.

Concept / Approach:
These properties mirror many bacterial plasma membranes, which host respiratory chains and maintain proton gradients across their single membrane. In contrast, the outer mitochondrial membrane resembles other eukaryotic membranes, being more permeable due to porins.

Step-by-Step Solution:

Verification / Alternative check:
Biochemical analyses show high protein-to-lipid ratio and presence of respiratory complexes similar to those found in bacteria.

Why Other Options Are Wrong:

• Outer mitochondrial membrane: different permeability and protein composition.
• Cell plasma membrane/nuclear envelope/ER: do not house a full respiratory chain nor maintain such tight proton impermeability.

Common Pitfalls:
Assuming all cellular membranes are compositionally similar; specialized functions drive distinct compositions.

Final Answer:
Some bacterial plasma membranes