The two subunits of ribosomes get associated in the presence of the following ion

Options

A. `Mg^(+2)`
B. `Ca^(+2)`
C. `Fe^(+2)`
D. `Fe^(+3)`

Answer

To solve the question regarding the ion that facilitates the association of the two subunits of ribosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Ribosomes**:
- Ribosomes are small organelles composed of two subunits: a smaller subunit and a larger subunit.

2. **Identify the Role of Ions**:
- The association of these two subunits is crucial for protein synthesis. Certain ions play a role in stabilizing this association.

3. **Examine the Given Options**:
- The options provided are:
- (a) Mg²⁺ (magnesium ion)
- (b) Ca²⁺ (calcium ion)
- (c) Fe²⁺ (iron(II) ion)
- (d) Fe³⁺ (iron(III) ion)

4. **Recall the Function of Each Ion**:
- Magnesium ions (Mg²⁺) are known to be essential for the structural integrity of ribosomes and are involved in the binding of the ribosomal subunits.
- Calcium ions (Ca²⁺) are more commonly associated with signaling and muscle contraction.
- Iron ions (Fe²⁺ and Fe³⁺) are primarily involved in oxygen transport and redox reactions, not in ribosome assembly.

5. **Conclude the Correct Answer**:
- Based on the information, magnesium ions (Mg²⁺) are required for the association of the ribosomal subunits. Therefore, the correct answer is (a) Mg²⁺.

### Final Answer:
The two subunits of ribosomes get associated in the presence of Mg²⁺ ions.

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