Which of the following structure of adapter molecule looks like a clover leaf?

Options

A. Secondary
B. Tertiary
C. Primary
D. Quaternary

Answer

To determine which structure of the adapter molecule looks like a clover leaf, we need to analyze the options provided in the question: secondary, tertiary, primary, or quaternary structure.

### Step-by-Step Solution:

1. **Identify the Adapter Molecule**: The question refers to an "adapter molecule," which in the context of biology is often identified as tRNA (transfer RNA).

2. **Understand tRNA Structure**: tRNA molecules are responsible for bringing amino acids to the ribosome during protein synthesis. Each tRNA has a specific sequence of nucleotides that allows it to recognize and bind to the corresponding codon on mRNA.

3. **Examine the Types of Structures**:
- **Primary Structure**: This refers to the linear sequence of nucleotides in the tRNA molecule.
- **Secondary Structure**: This is where the tRNA folds into specific shapes due to hydrogen bonding between complementary bases. The secondary structure of tRNA is often depicted as a clover leaf.
- **Tertiary Structure**: This refers to the three-dimensional shape of the tRNA molecule, which is more complex and can resemble an L-shape.
- **Quaternary Structure**: This involves the assembly of multiple polypeptide chains into a functional protein, which is not applicable to tRNA.

4. **Identify the Clover Leaf Structure**: The clover leaf structure is characteristic of the secondary structure of tRNA. It consists of four stems and three loops, which give it the appearance of a clover leaf.

5. **Conclusion**: Based on the analysis, the correct answer to the question is **secondary structure**.

### Final Answer:
The structure of the adapter molecule that looks like a clover leaf is the **secondary structure** of tRNA.