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Question #46531
The Question
HIV evades the host's adaptive immune system by rapidly altering the epitopes of its envelope glycoproteins, rendering pre-existing antibodies from memory B-cells ineffective. This rapid antigenic variation is primarily driven by the error-prone nature of Reverse Transcriptase. In this context, how does the 'degeneracy of the genetic code' specifically aid the virus in maintaining its evolutionary fitness despite such a high mutation rate?
Options
- A.
It ensures that every nucleotide substitution introduced by Reverse Transcriptase results in a novel amino acid, maximizing antigenic shift against memory B-cells.
- B.
It acts as a genetic buffer, allowing the accumulation of silent mutations that preserve essential viral enzyme domains while non-synonymous mutations alter hypervariable surface epitopes.
- C.
It enables the Reverse Transcriptase enzyme to utilize a 3' to 5' exonuclease proofreading mechanism to correct lethal mutations before integration into the host macrophage genome.
- D.
It shifts the reading frame of the viral mRNA during translation, allowing a single RNA transcript to produce multiple distinct antigenic variants to exhaust Helper T-cells.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Reverse_Transcriptase|Integrase|Genetic_Code_Degeneracy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often equate 'high mutation rate' purely with 'rapid changes in all proteins'.
They fail to synthesize that without the buffering effect of genetic code degeneracy (wobble hypothesis), a high mutation rate would be lethal to the virus.
Degeneracy acts as a shock absorber, allowing structural conservation of essential internal enzymes while permitting surface epitope variation for immune evasion.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Health and Disease - Class 12 |
| Concept | HIV Replication Cycle |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |