Question

Match the List I with that of List II and select the right answer
List-I:
(A). Kappa Casein
(B). \(\beta\) - Lactoglobulin
(C). Non protein Nitrogen
(D). \(\alpha\) - Lactalbumin
List-II:
(I). Lactose biosynthesis
(II). Retinol
(III). Chymosin
(IV). Soluble in 12% TCA
Choose the correct answer from the options given below

• (A) - (III), (B) - (II), (C) - (I), (D) - (IV)
• (A) - (II), (B) - (III), (C) - (IV), (D) - (I)
• (A) - (III), (B) - (II), (C) - (IV), (D) - (I)
• (A) - (IV), (B) - (II), (C) - (I), (D) - (III)

Hint:

Remember that \(\alpha\)-Lactalbumin is the key modifier protein for lactose synthesis in the mammary gland, and Kappa-casein is the specific target of chymosin.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Milk contains complex macromolecular proteins and non-protein nitrogenous elements, each participating in specific chemical, biological, and metabolic pathways.

Step 2: Detailed Explanation:
Let us analyze each component for pairing:

• (A) Kappa Casein: Specifically targeted and cleaved by the enzyme Chymosin (rennet) at the Phe-105–Met-106 peptide bond to destabilize the casein micelle, initiating curd formation. Thus, \(A \rightarrow \text{III}\).

• (B) \(\beta\)-Lactoglobulin: The major whey protein of bovine milk, containing a hydrophobic pocket that functions biologically as a transport protein for Retinol (Vitamin A). Thus, \(B \rightarrow \text{II}\).

• (C) Non-Protein Nitrogen (NPN): Defined analytically as the fraction of nitrogen compounds in milk that do not precipitate and remain soluble in a 12% trichloroacetic acid (TCA) solution. Thus, \(C \rightarrow \text{IV}\).

• (D) \(\alpha\)-Lactalbumin: Forms the regulatory subunit of the lactose synthase enzyme complex, directly controlling lactose biosynthesis in the mammary gland. Thus, \(D \rightarrow \text{I}\).
This results in the matching sequence: (A)-(III), (B)-(II), (C)-(IV), (D)-(I).

Step 3: Final Answer
The correct matching sequence is (A) - (III), (B) - (II), (C) - (IV), (D) - (I).