Question

Proteins are polymers of \(\alpha\)-amino acids which are joined to each other by :

• A. Covalent Bond
• B. Peptide Bond
• C. Glycosidic Bond
• D. Coordinate Bond

Hint:

To remember biological linkages: 1. Proteins \(\rightarrow\) Peptide. 2. Polysaccharides \(\rightarrow\) Glycosidic. 3. Nucleic Acids \(\rightarrow\) Phosphodiester.

Answer 1

The Correct Option is B

Concept: Proteins are biological macromolecules. They are polymers where the repeating monomeric units are \(\alpha\)-amino acids. Each amino acid contains:

• An amino group (\(-\text{NH}_2\)).

• A carboxyl group (\(-\text{COOH}\)).

• A hydrogen atom and a variable side chain (R) attached to the same \(\alpha\)-carbon.
Step 1: Understanding the polymerization process.
When two amino acids join, the carboxyl group (\(-\text{COOH}\)) of one amino acid reacts with the amino group (\(-\text{NH}_2\)) of the next amino acid. This is a condensation reaction that involves the loss of a water molecule (\(\text{H}_2\text{O}\)).

Step 2: Defining the resulting linkage.
The resulting \(-\text{CO}-\text{NH}-\) linkage is specifically termed a peptide bond (or peptide linkage). When many such bonds are formed, the resulting chain is called a polypeptide. A protein consists of one or more such polypeptide chains.

Step 3: Eliminating other options.

• Covalent bond: While a peptide bond is a type of covalent bond, the term is too general.

• Glycosidic bond: These link monosaccharide units in carbohydrates.

• Coordinate bond: These involve the sharing of an electron pair from a single atom, typically found in complex compounds.