Which of the following combination are correct in case of proteins ?

Options

A. `alpha` - helix of protein _________ secondary structure
B. Sequence of Amino acids _________ Primary structure
C. Denaturation __________ Breaking of peptide bonds
D. `beta` - plated sheet _________ quaternarystructure

Explanation

To solve the problem of identifying the correct combinations in the context of proteins, we will analyze each option step by step.

### Step 1: Understand the Structures of Proteins
Proteins have different structural levels:
- **Primary Structure**: The sequence of amino acids in a polypeptide chain.
- **Secondary Structure**: Local folding of the polypeptide chain into structures such as alpha helices and beta-pleated sheets.
- **Tertiary Structure**: The overall three-dimensional shape of a single polypeptide chain.
- **Quaternary Structure**: The arrangement of multiple polypeptide chains into a functional protein complex.

### Step 2: Analyze Each Combination
1. **Alpha Helix and Secondary Structure**
- The alpha helix is indeed a type of secondary structure.
- **Conclusion**: This combination is correct.

2. **Sequence of Amino Acids and Primary Structure**
- The sequence of amino acids defines the primary structure of a protein.
- **Conclusion**: This combination is correct.

3. **Denaturation and Breaking of Peptide Bonds**
- Denaturation refers to the unfolding of a protein, which may involve breaking hydrogen bonds and other interactions, but does not typically break peptide bonds (which are covalent bonds).
- **Conclusion**: This combination is incorrect.

4. **Beta-Pleated Sheet and Quaternary Structure**
- The beta-pleated sheet is a type of secondary structure, not a quaternary structure.
- **Conclusion**: This combination is incorrect.

### Step 3: Final Assessment
From the analysis above, the correct combinations are:
- **Alpha Helix with Secondary Structure** (Correct)
- **Sequence of Amino Acids with Primary Structure** (Correct)
- **Denaturation with Breaking of Peptide Bonds** (Incorrect)
- **Beta-Pleated Sheet with Quaternary Structure** (Incorrect)

### Final Answer
The correct combinations are:
- **A. Alpha Helix - Secondary Structure**
- **B. Sequence of Amino Acids - Primary Structure**