Question

Lectins are:

• A. Proteins that bind carbohydrates with high specificity
• B. Dominant surface feature of the outer membrane of gram negative bacteria
• C. Membrane lipids of eucaryotic cells
• D. Fibrous, tough, water insoluble substances found in plant cell wall

Hint:

Remember:
• Lectins \(\rightarrow\) Carbohydrate-binding proteins
• LPS \(\rightarrow\) Gram-negative bacterial outer membrane
• Cellulose/Lignin \(\rightarrow\) Plant cell wall components

Answer 1

The Correct Option is A

Concept: Lectins are specialized proteins that have the ability to recognize and bind specifically to carbohydrate molecules. They are widely found in plants, animals, and microorganisms and play important roles in:
• Cell-cell recognition
• Immune responses
• Cell signaling
• Agglutination of cells They bind selectively to sugar residues without altering the carbohydrate chemically.

Step 1: Understanding the meaning of lectins. Lectins are proteins that possess specific binding sites for carbohydrates. Their main characteristic is: \[ \text{Lectin} \rightarrow \text{Specific carbohydrate-binding protein} \] Thus, option (A) correctly defines lectins.

Step 2: Eliminating the incorrect options.
• Option (B): Refers to lipopolysaccharides (LPS), which are dominant components of the outer membrane of gram-negative bacteria.
• Option (C): Refers to membrane lipids such as phospholipids and glycolipids found in eukaryotic cells.
• Option (D): Refers mainly to cellulose and lignin, which are structural materials in plant cell walls. Hence, only option (A) matches the definition of lectins. \[ \boxed{\text{Lectins are proteins that bind carbohydrates with high specificity}} \]