Select one which is not true for ribosomes.

Options

A. Made of two subunits
B. From polysome
C. May attach to mRNA
D. Have no role in protein synthesis

Explanation

### Step-by-Step Solution:

1. **Understanding Ribosomes**: Ribosomes are cellular structures that play a crucial role in protein synthesis. They are often referred to as the "protein factories" of the cell.

2. **Structure of Ribosomes**: Ribosomes are composed of two subunits: a larger subunit and a smaller subunit. In prokaryotes, the ribosome is classified as 70S (with subunits 50S and 30S), while in eukaryotes, it is classified as 80S (with subunits 60S and 40S).

3. **Function of Ribosomes**: The primary function of ribosomes is to synthesize proteins by translating messenger RNA (mRNA) into polypeptide chains. This process is known as translation.

4. **Polysomes Formation**: Ribosomes can form polysomes, which are clusters of ribosomes translating a single mRNA strand simultaneously. This enhances the efficiency of protein synthesis.

5. **Evaluating the Statements**: The question asks to select the statement that is NOT true about ribosomes. The options include:
- They are made up of two subunits (True)
- They form polysomes (True)
- They may attach to mRNA (True)
- They have no role in protein synthesis (NOT True)

6. **Conclusion**: The statement "has no role in protein synthesis" is incorrect, as ribosomes are essential for this process. Therefore, this is the answer to the question.

### Final Answer:
The statement that is NOT true for ribosomes is: "They have no role in protein synthesis."

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