The Question is from neet-botany biomolecules-biology nucleic-acid, and it was created by the author D VINOD

Question

A novel virus is discovered with a single-stranded nucleic acid genome.  Treatment with RNase H significantly reduces its infectivity, while DNase I has no effect.  Further analysis reveals the presence of short RNA fragments complementary to the genome. What can be most confidently inferred about the viral genome?

D VINOD · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Viral replication mechanisms and the action of nucleases.
 **Related Topics**: RNA viruses, DNA viruses, reverse transcription, RNA-dependent RNA polymerase.
 **Prerequisites**: Understanding of enzyme function (RNase H, DNase I), nucleic acid structure (ssRNA, dsRNA, DNA), and basic viral replication strategies.
## SOLUTION PATHWAY
**Given Information**:
  * The virus has a single-stranded nucleic acid genome.
  * RNase H reduces infectivity.
  * DNase I has no effect.
  * Short RNA fragments complementary to the genome are present.
**Method & Steps**:
 1. Analyze the effect of RNase H: RNase H specifically degrades the RNA strand of an RNA:DNA hybrid.  The fact that RNase H reduces infectivity strongly suggests that the virus utilizes an RNA:DNA hybrid during its replication cycle.
  Reasoning:  RNase H's action implies the presence of an RNA:DNA hybrid, a characteristic of reverse transcription.
  Formula/Rule: None directly applicable.
 2. Analyze the effect of DNase I: DNase I degrades DNA.  The lack of effect from DNase I indicates that DNA is not a primary component of the viral genome itself.
  Working:  If the genome were DNA, DNase I would reduce infectivity.
  Key Point: The absence of an effect from DNase I excludes options involving a DNA genome.
 3. Consider the complementary RNA fragments: The presence of short RNA fragments complementary to the genome suggests the existence of a double-stranded RNA intermediate during replication. This intermediate would be formed during the process of RNA replication.
  Result: The virus is most likely a single-stranded RNA virus that replicates via a double-stranded RNA intermediate.
  Verification: This explanation is consistent with all the given observations.
 ## OPTION ANALYSIS
A :x:  While it involves an RNA virus, the lack of DNase I effect contradicts a DNA intermediate.
B :x:  The DNase I result contradicts a DNA genome.
 C ✓: This option aligns perfectly with all observations: ssRNA genome, RNase H sensitivity (indicating RNA:DNA hybrid during reverse transcription, albeit not directly), and complementary RNA fragments indicating a dsRNA intermediate.
D :x: The presence of complementary RNA fragments suggests a replication step involving a double-stranded intermediate, but not necessarily a double-stranded genome.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Misinterpreting RNase H's action:  Focusing solely on RNA degradation without considering the RNA:DNA hybrid context.
  2.Ignoring the complementary RNA fragments:  Overlooking the significance of these fragments as evidence of a dsRNA intermediate.
 **Quick Tips**:
  1.Consider the specificities of the enzymes used in the experiment.
  2.Remember that many RNA viruses utilize intermediates during replication.

D VINOD · Answer

It is a single-stranded RNA virus that replicates through a DNA intermediate.

D VINOD · Answer

It is a single-stranded DNA virus that replicates through an RNA intermediate.

D VINOD · Answer

The correct Option is "It is a single-stranded RNA virus that replicates through a double-stranded RNA intermediate."

D VINOD · Answer

It is a double-stranded RNA virus.

NEET Botany Biology Biomolecules Nucleic Acid MCQs

Select Topic

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

NEET Subjects

Our Bots

Company