Which of the following is responsible for the mechanical support, protein synthesis and enzyme transport?

Options

A. Option1 cell membrane
B. Option2 mitochondria
C. Option3 dictyosome
D. Option4 endoplasmic reticulum.

Explanation

To solve the question "Which of the following is responsible for the mechanical support, protein synthesis, and enzyme transport?", we need to analyze the functions of the given cell organelles.

### Step-by-Step Solution:

1. **Understanding the Functions**:
- We need to identify which organelle is responsible for mechanical support, protein synthesis, and enzyme transport.

2. **Evaluating the Options**:
- **Cell Membrane**: This is primarily a lipid bilayer that maintains the shape of the cell and regulates what enters and exits the cell. It does not primarily function in protein synthesis or enzyme transport.
- **Mitochondria**: Known as the powerhouse of the cell, mitochondria are involved in cellular respiration and energy production (ATP generation). They do not play a direct role in protein synthesis or mechanical support.
- **Dictyosomes (Golgi Apparatus)**: These are involved in packaging, storage, and transport of molecules, particularly proteins and lipids. However, they do not directly synthesize proteins.
- **Endoplasmic Reticulum (ER)**: The ER is a network of membranes involved in the synthesis of proteins (rough ER) and lipids, as well as the transport of these molecules within the cell. It also provides mechanical support through its structure.

3. **Identifying the Correct Answer**:
- Based on the functions evaluated, the Endoplasmic Reticulum is the only organelle that provides mechanical support, is involved in protein synthesis, and facilitates enzyme transport.

### Conclusion:
The correct answer is **Endoplasmic Reticulum**.