Outer and inner membranes of mitochondria are

Options

A. structrually and functionally similar
B. structurally different but functionally similar
C. structurally similar but functionally different.
D. Structurally and functionally different.

Answer

### Step-by-Step Solution:

1. **Understanding Mitochondria**: Mitochondria are double-membranous organelles found in eukaryotic cells, primarily responsible for ATP (energy) production.

2. **Identifying the Membranes**: Mitochondria have two membranes:
- **Outer Membrane**: This membrane is smooth and serves as a barrier between the cytosol and the inner environment of the mitochondria.
- **Inner Membrane**: This membrane is highly folded into structures known as cristae, which increase the surface area for chemical reactions.

3. **Analyzing Structural Differences**:
- The **outer membrane** is smooth and does not have folds.
- The **inner membrane** has infoldings (cristae) which are essential for its functions.

4. **Analyzing Functional Differences**:
- The **outer membrane** is permeable to small molecules and ions, facilitating the passage of substances in and out of the mitochondria.
- The **inner membrane** is semi-permeable and regulates the passage of specific molecules, such as enzymes and ATP, playing a crucial role in the metabolic processes of the mitochondria.

5. **Conclusion**: Based on the structural and functional analysis, we can conclude that the outer and inner membranes of mitochondria are:
- **Structurally different** (due to the smooth outer membrane versus the folded inner membrane).
- **Functionally different** (with distinct roles in molecular passage and ATP production).

Thus, the correct answer is that the outer and inner membranes of mitochondria are **structurally and functionally different**.