Ribosomes are attached to ER through

Options

A. rRNA
B. Hydrophobic attraction
C. Ribophorins
D. tRNA

Answer

**Step-by-Step Solution:**

1. **Understanding Ribosomes**: Ribosomes are cellular structures that function as the site of protein synthesis. They are composed of two subunits, a larger subunit and a smaller subunit.

2. **Types of Ribosomes**: In eukaryotic cells, ribosomes are classified as 80S, which means they consist of a larger subunit (60S) and a smaller subunit (40S).

3. **Role of Endoplasmic Reticulum (ER)**: The endoplasmic reticulum (ER) is an organelle that plays a crucial role in the synthesis of proteins and lipids. Ribosomes can be found attached to the rough endoplasmic reticulum (RER), which is involved in protein synthesis.

4. **Attachment Mechanism**: The question asks how ribosomes are attached to the endoplasmic reticulum. The attachment occurs through specific glycoproteins.

5. **Identifying the Correct Glycoprotein**: The glycoproteins responsible for the attachment of ribosomes to the ER are known as riboforins. These riboforins facilitate the binding of the ribosomal subunits to the membrane of the ER.

6. **Conclusion**: Therefore, the correct answer to the question "Ribosomes are attached to ER through" is option three: riboforins.

**Final Answer**: Ribosomes are attached to the endoplasmic reticulum through riboforins.

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