Q.42 Group I lists spectroscopic methods and Group II lists biomolecular applications of these
methods. Match the methods in Group I with the applications in Group II.
Group I Group II
P. Infrared 1. Identification of functional groups
Q. Circular Dichroism 2. Determination of secondary structure
R. Nuclear Magnetic Resonance 3. Estimation of molecular weight
4. Determination of 3–D structure
(A) P–4, Q–3, R–1 (B) P–2, Q–1, R–3
(C) P–1, Q–2, R–4 (D) P–3, Q–2, R–4
Infrared, Circular Dichroism, and Nuclear Magnetic Resonance represent core spectroscopic methods matched to biomolecular applications like functional group identification, secondary structure determination, and 3D structure analysis in biotechnology exams such as GATE. This matching tests fundamental knowledge of their principles and uses in molecular biology. The correct pairing is option (C): P-1, Q-2, R-4.
Method Applications
Infrared (IR) spectroscopy identifies functional groups by detecting vibrational transitions in molecular bonds, such as C=O stretches at ~1700 cm⁻¹ or N-H at ~3300 cm⁻¹, making it ideal for biomolecules like proteins and nucleic acids.
Circular Dichroism (CD) measures differential absorption of circularly polarized light to assess secondary structures, distinguishing α-helices (negative peak ~222 nm) from β-sheets (~218 nm) in proteins.
Nuclear Magnetic Resonance (NMR) determines high-resolution 3D structures of biomolecules through NOE correlations and scalar couplings, enabling atomic-level modeling of proteins and nucleic acids.
Option Analysis
Option (A) P-4, Q-3, R-1 incorrectly assigns IR to 3D structure (suited for NMR), CD to molecular weight (typically gel filtration or MS), and NMR to functional groups (IR’s domain).
Option (B) P-2, Q-1, R-3 mismatches IR to secondary structure (CD’s strength), CD to functional groups (IR primary), and NMR to molecular weight (not its core biomolecular use).
Option (C) P-1, Q-2, R-4 correctly links IR-functional groups, CD-secondary structure, and NMR-3D structure, aligning with standard applications. ✅
Option (D) P-3, Q-2, R-4 wrongly pairs IR with molecular weight estimation.
GATE Exam Insights
This question from GATE Biotechnology 2019 emphasizes spectroscopic tools in biomolecular characterization, where IR excels in rapid functional group scans, CD in folding studies, and NMR in structural genomics. Molecular weight estimation (option 3) relies more on SDS-PAGE or mass spectrometry, not listed methods. Understanding these distinctions aids quantitative analysis in enzyme kinetics and protein engineering.
🎯 Quick Reference Matching
P. Infrared → 1. Functional Groups
Q. Circular Dichroism → 2. Secondary Structure
R. NMR → 4. 3D Structure
Correct Answer: (C) P-1, Q-2, R-4
