Proteins are characterized by the linkage

Options

A. `-undersetundersetN|overset|C-H-oversetoverset(O)(||)N`
B. `H-O-C-=N`
C. `-underset|oversetoversetN|C-oversetoverset(O)(||)N-`
D. `-oversetoverset(O)(||)C-oversetoversetH|N-`

Explanation

To solve the question "Proteins are characterized by the linkage," we need to identify the specific type of bond that links amino acids together to form proteins. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Proteins**:
- Proteins are large biomolecules made up of smaller units called amino acids.

2. **Amino Acids**:
- Each amino acid contains an amino group (-NH2), a carboxyl group (-COOH), and a unique side chain (R group) that distinguishes one amino acid from another.

3. **Linkage Between Amino Acids**:
- Amino acids are linked together through a specific type of bond known as a peptide bond.

4. **Formation of Peptide Bonds**:
- A peptide bond forms when the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water (H2O). This reaction is known as a condensation reaction.

5. **Structure of Peptide Bond**:
- The resulting bond between the two amino acids is characterized by a carbon atom (C) double-bonded to an oxygen atom (O) and single-bonded to a nitrogen atom (N) from the amino group of the next amino acid.

6. **Conclusion**:
- Therefore, proteins are characterized by the peptide linkage (or peptide bond) that connects the amino acids together in a polypeptide chain.

### Final Answer:
Proteins are characterized by the peptide linkage.