The endoplasmic reticulum that is not studded with ribosomes on its surface is the major site for synthesis of

Options

A. proteins
B. Carbohydrates
C. lipids
D. all of these

Answer

To answer the question regarding the endoplasmic reticulum that is not studded with ribosomes on its surface, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Types of Endoplasmic Reticulum (ER)**:
- There are two types of endoplasmic reticulum: Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).
- RER has ribosomes on its surface, while SER does not.

2. **Understand the Function of RER**:
- The Rough Endoplasmic Reticulum is primarily involved in the synthesis of proteins due to the presence of ribosomes.

3. **Understand the Function of SER**:
- The Smooth Endoplasmic Reticulum, lacking ribosomes, is not involved in protein synthesis. Instead, it plays a crucial role in the synthesis of lipids, including steroid hormones.

4. **Analyze the Options Given**:
- The options provided are proteins, carbohydrates, lipids, and all of these.
- Since SER is the focus of the question and is responsible for lipid synthesis, we can eliminate proteins (which are synthesized in RER) and carbohydrates (which are not primarily synthesized in SER).

5. **Conclude the Correct Answer**:
- The major site for synthesis in the Smooth Endoplasmic Reticulum is lipids. Therefore, the correct answer is **lipids**.

### Final Answer:
The endoplasmic reticulum that is not studded with ribosomes on its surface is the major site for the synthesis of **lipids**.

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