The structural components of endoplasmic reticulum are

Options

A. Cisternae
B. Tubules
C. Vesicles
D. All the above

Answer

To answer the question regarding the structural components of the endoplasmic reticulum (ER), we can break down the information as follows:

### Step-by-Step Solution:

1. **Understanding Endoplasmic Reticulum**:
- The endoplasmic reticulum is a membrane-bound organelle found in eukaryotic cells. It plays a crucial role in the synthesis of proteins and lipids.

2. **Identifying Structural Components**:
- The endoplasmic reticulum is primarily made up of membranes. These membranes are composed of a lipid bilayer, which includes phospholipids and proteins.

3. **Types of Endoplasmic Reticulum**:
- There are two types of endoplasmic reticulum:
- **Rough Endoplasmic Reticulum (RER)**: Studded with ribosomes on its cytoplasmic surface, which gives it a "rough" appearance. It is involved in protein synthesis.
- **Smooth Endoplasmic Reticulum (SER)**: Lacks ribosomes and is involved in lipid synthesis and detoxification processes.

4. **Additional Components**:
- The endoplasmic reticulum is also associated with other cellular structures:
- **Nuclear Envelope**: The double membrane surrounding the nucleus, which is continuous with the endoplasmic reticulum.
- **Cisternae**: Flattened membrane-bound sacs that make up the ER.

5. **Conclusion**:
- The structural components of the endoplasmic reticulum include the lipid bilayer membranes, ribosomes (in the case of RER), and associated structures like the nuclear envelope.

### Final Answer:
The structural components of the endoplasmic reticulum include lipid bilayer membranes, ribosomes (in the case of rough ER), and associated structures like the nuclear envelope.

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