RER is found abundantly in those cells which are actively involved in

Options

A. protein synthesis
B. Lipid synthesis
C. steroidal hormones synthesis
D. Dictyosome

Answer

### Step-by-Step Text Solution

1. **Understanding RER**: The Rough Endoplasmic Reticulum (RER) is a type of endoplasmic reticulum that is characterized by the presence of ribosomes on its surface. This gives it a "rough" appearance under a microscope.

2. **Function of RER**: The primary function of the RER is to synthesize proteins. The ribosomes attached to its membrane are the sites where protein synthesis occurs. These proteins can be secreted from the cell, incorporated into the cell membrane, or sent to lysosomes.

3. **Cells with Abundant RER**: Cells that are actively involved in protein synthesis will have a high abundance of RER. Examples of such cells include pancreatic cells, which produce digestive enzymes, and fibroblasts, which synthesize collagen and other extracellular matrix components.

4. **Analyzing the Options**:
- **Option 1: Protein Synthesis** - This is correct as RER is directly involved in the synthesis of proteins.
- **Option 2: Lipid Synthesis** - This is incorrect; lipid synthesis occurs in the Smooth Endoplasmic Reticulum (SER), not RER.
- **Option 3: Steroidal Hormone Synthesis** - This is also incorrect; steroidal hormone synthesis is a function of the SER.
- **Option 4: Dictyosome** - This option is incorrect as well; dictyosomes are part of the Golgi apparatus and are involved in processing and packaging proteins.

5. **Conclusion**: Based on the above analysis, the correct answer to the question is that RER is found abundantly in those cells which are actively involved in **protein synthesis**.