Percentage of cell membranes contained in E.R. is

Options

A. 10-20%
B. 20-30%
C. 30-60%
D. 60-75%

Answer

To determine the percentage of cell membranes contained in the endoplasmic reticulum (E.R.), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Endoplasmic Reticulum (E.R.):**
- The E.R. is a network of membranes within the cell. It plays a crucial role in the synthesis of proteins and lipids.

2. **Identify the Function of the E.R.:**
- The E.R. is involved in the production of transmembrane proteins and lipids, which are essential components of cell membranes.

3. **Consider the Total Membrane Content in Cells:**
- The cell has various organelles, each contributing to the overall membrane content. The E.R. is one of the largest membrane systems in the cell.

4. **Review the Given Options:**
- The options provided for the percentage of cell membranes contained in the E.R. are:
- A) 10 to 20 percent
- B) 20 to 30 percent
- C) 30 to 60 percent
- D) 60 to 75 percent

5. **Analyze the Contribution of the E.R. to Membrane Content:**
- Based on biological studies, it is established that the E.R. constitutes a significant portion of the total membrane system in eukaryotic cells.

6. **Select the Correct Option:**
- The endoplasmic reticulum is known to account for approximately 30 to 60 percent of the total membrane content in a cell. Therefore, the correct answer is option C) 30 to 60 percent.

### Final Answer:
The percentage of cell membranes contained in the endoplasmic reticulum (E.R.) is **30 to 60 percent**.

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