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Question #45411
The Question
HIV entry into Helper T-cells requires the CD4 receptor and a co-receptor (such as CCR5 or CXCR4, which belong to the G-protein coupled receptor family). Following massive acute viral entry, researchers observe that these T-cells exhibit a severely blunted secondary messenger (cAMP) response when exposed to specific endogenous chemokines. Which of the following best explains this transient cellular desensitization?
Options
- A.
Massive viral fusion and entry lead to the internalization and functional depletion of surface GPCR co-receptors, preventing endogenous ligand binding.
- B.
Viral reverse transcriptase directly binds to and inhibits membrane-bound adenylate cyclase, halting the conversion of ATP to cAMP.
- C.
The viral RNA genome acts as a competitive inhibitor for intracellular secondary messengers like IP3 and calcium ions.
- D.
HIV envelope glycoproteins permanently alter the host cell membrane permeability, causing rapid leakage of pre-formed cAMP into the extracellular fluid.
Check Your Answer
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
GPCR|cAMP|HIV_gp120
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating 'Human Health and Disease' (HIV life cycle) with 'Chemical Coordination' (Mechanism of hormone action).
Students often memorize that HIV destroys T-cells over time, but fail to recognize the immediate physical consequence of viral entry: the massive internalization of GPCR co-receptors physically removes the very structures required for normal secondary messenger signaling.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Chemical Coordination and Integration - Class 11 |
| Concept | Hypothalamo-Hypophyseal Portal System |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |