In eukaryotes , which of these rRNA is not synthesized by RNA Polymerase I ?

Options

A. 28S rRNA
B. 5S rRNA
C. 5.8S rRNA
D. 18S rRNA

Answer

To solve the question regarding which rRNA is not synthesized by RNA Polymerase I in eukaryotes, we can follow these steps:

### Step 1: Understand the Types of RNA Polymerases in Eukaryotes
Eukaryotic cells have three main types of RNA polymerases:
- **RNA Polymerase I**: Synthesizes rRNA (except 5S rRNA).
- **RNA Polymerase II**: Synthesizes mRNA and some snRNA.
- **RNA Polymerase III**: Synthesizes tRNA, 5S rRNA, and some other small RNAs.

**Hint**: Remember the function of each RNA polymerase in eukaryotes.

### Step 2: Identify the rRNA Types
The question lists the following rRNA types:
- 28S rRNA
- 5S rRNA
- 5.8S rRNA
- 18S rRNA

**Hint**: Familiarize yourself with the different types of rRNA and which polymerase synthesizes each.

### Step 3: Determine Which rRNA is Synthesized by RNA Polymerase I
From the information:
- **RNA Polymerase I** synthesizes:
- 28S rRNA
- 18S rRNA
- 5.8S rRNA

**Hint**: Focus on which of these rRNAs are specifically mentioned to be synthesized by RNA Polymerase I.

### Step 4: Identify the rRNA Not Synthesized by RNA Polymerase I
The only rRNA from the list that is not synthesized by RNA Polymerase I is:
- **5S rRNA**, which is synthesized by RNA Polymerase III.

**Hint**: Look for the rRNA that is excluded from the synthesis by RNA Polymerase I.

### Conclusion
The rRNA that is not synthesized by RNA Polymerase I in eukaryotes is **5S rRNA**.

**Final Answer**: 5S rRNA