Which is must for binding of sub units of ribosomes ?

Options

A. `Mg^(++) `
B. `Ca^(++)`
C. `Fe^(++)`
D. Mg and Si

Answer

To answer the question "Which is must for binding of subunits of ribosomes?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand Ribosome Structure**:
- Ribosomes are made up of two subunits. In prokaryotes, these subunits are referred to as 50S and 30S, which combine to form a 70S ribosome. In eukaryotes, the subunits are 60S and 40S, forming an 80S ribosome.

2. **Identify the Role of Ions**:
- The binding of these ribosomal subunits requires certain ions. Ions play a crucial role in stabilizing the structure of ribosomes and facilitating the interaction between the subunits.

3. **Determine the Necessary Ion**:
- Among the options provided (magnesium, calcium, iron, magnesium and silicon), we need to identify which ion is essential for the binding of ribosomal subunits.

4. **Select the Correct Ion**:
- Magnesium ions (Mg²⁺) are known to be essential for the binding of ribosomal subunits. They help in stabilizing the ribosomal structure and are involved in the assembly of the ribosome.

5. **Eliminate Incorrect Options**:
- Calcium is not required for ribosome subunit binding. Iron and silicon also do not play a role in this process. Therefore, the only correct option is magnesium.

6. **Conclusion**:
- The correct answer to the question is **magnesium**.

### Final Answer:
- Magnesium is must for binding of subunits of ribosomes.