Q.28 Some microbes survive or grow at very high temperatures because of
1. heat-shock protein synthesis
2. molecular chaperones to prevent or repair protein denaturation
3. thermostability of enzymes
4. heat-shock protein synthesis, molecular chaperones to prevent or repair protein denaturation
and thermostability of enzymes
Thermophiles Survival: Heat Tolerance Mechanisms in Microbes
Certain microbes called thermophiles thrive at high temperatures above 60°C due to specialized adaptations preventing protein damage. This SEO article analyzes a biology MCQ on heat resistance, identifying the correct answer with comprehensive option explanations for exam success.
Correct Answer
The right choice is option 4: heat-shock protein synthesis, molecular chaperones to prevent or repair protein denaturation and thermostability of enzymes.
Thermophiles like those in hot springs employ multiple mechanisms: heat-shock proteins (HSPs) induced by stress, molecular chaperones (Hsp70, GroEL) that refold denatured proteins or prevent aggregation, and enzymes with stable structures from disulfide bonds or hydrophobic cores. This combination ensures functionality at extreme heat where mesophilic proteins unfold.
Option Breakdown
Option 1 Analysis
Statement: Heat-shock protein synthesis.
Why Incorrect: HSPs like Hsp70 are crucial for refolding but represent only one layer; microbes also need stable enzymes and broader chaperone networks for complete survival.
Option 2 Analysis
Statement: Molecular chaperones to prevent or repair protein denaturation.
Why Incorrect: Chaperones (Hsp90, small HSPs) prevent aggregation and aid refolding under proteotoxic stress, yet lack thermostable enzymes, limiting standalone efficacy at sustained high temperatures.
Option 3 Analysis
Statement: Thermostability of enzymes.
Why Incorrect: Heat-stable enzymes with rigid structures resist denaturation, but without chaperones or HSPs, unfolded proteins accumulate, overwhelming cellular proteostasis.
Option 4 Analysis
Statement: Heat-shock protein synthesis, molecular chaperones to prevent or repair protein denaturation and thermostability of enzymes.
Why Correct: Integrated system—HSPs trigger chaperone response, chaperones manage misfolding (accelerating native folding over aggregation), and thermostable enzymes maintain metabolism; essential for hyperthermophiles like Pyrococcus furiosus.
Exam Relevance
This topic tests extremophile adaptations in NEET and microbiology curricula, linking protein quality control to biotechnology applications like PCR enzymes from Thermus aquaticus.
