The Question is from neet-botany molecular-basis-of-inheritance genetic-code, and it was created by the author Mr. NARESH KUMAR K

Question

Certain mutations in tRNA can suppress nonsense mutations in mRNA. This phenomenon is MOST directly related to alterations in which part of the tRNA?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
 **Primary Concept**: Nonsense suppression by tRNA mutations
 **Related Topics**: Translation, genetic code, tRNA structure, nonsense mutations
 **Prerequisites**: Understanding of the process of translation, the role of tRNA in codon recognition, and the nature of nonsense mutations.
## SOLUTION PATHWAY
**Given Information**:
  Nonsense mutations in mRNA are suppressed by certain tRNA mutations.
  We need to identify the part of the tRNA most directly involved.
**Method & Steps**:
 1. Understand nonsense mutations: Nonsense mutations introduce premature stop codons (UAA, UAG, UGA) into the mRNA, leading to truncated and often non-functional proteins.
  Reasoning: These premature stops halt translation prematurely.
 2. Understand the role of tRNA in translation: tRNA molecules carry specific amino acids and recognize mRNA codons through their anticodons.  The anticodon loop is crucial for codon recognition.
  Working: A mutation in the tRNA anticodon could allow it to recognize a stop codon and insert an amino acid, thus suppressing the nonsense mutation.
 3. Consider the other tRNA parts: The acceptor stem binds the amino acid, the D-loop and TΨC loop are involved in tRNA structure and interaction with ribosomes, but they are not directly involved in codon recognition.
  Key Point: Only changes in the anticodon loop can directly alter the codon recognition properties of the tRNA.
 4. Identify the relevant tRNA region:
  Result: The anticodon loop is directly responsible for codon recognition.  A mutation in this region can allow a tRNA to recognize and bind to a stop codon, inserting an amino acid instead of terminating translation. This suppresses the nonsense mutation.
  Verification: The other options are not directly involved in codon recognition, hence they are less likely to suppress nonsense mutations.
 ## OPTION ANALYSIS
[A] :x: Acceptor stem: The acceptor stem is where the amino acid attaches to the tRNA. While important for translation, it doesn't directly interact with the mRNA codon.
[B] :x: D-loop: The D-loop is involved in tRNA structure and function but not directly in codon recognition.
[C] :x: TΨC loop: Similar to the D-loop, the TΨC loop is involved in tRNA structure and ribosome interaction, but not codon recognition.
[D] ✓: Anticodon loop: The anticodon loop contains the anticodon, which is complementary to the mRNA codon.  Mutations here can directly alter codon recognition, allowing a tRNA to bind to a stop codon and insert an amino acid, thus suppressing the nonsense mutation.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the roles of different tRNA regions: Students may incorrectly associate other tRNA regions with codon recognition.
  How to avoid: Carefully review the function of each tRNA region.
  2.Failing to understand the mechanism of nonsense suppression: Students may not grasp how a tRNA mutation can bypass a premature stop codon.
  How to avoid: Visualize the process of translation and how an altered anticodon can lead to the insertion of an amino acid at a stop codon.
 **Quick Tips**:
  1.Remember the central role of the anticodon in codon-anticodon pairing.
  2.Visualize the tRNA structure and locate the anticodon loop.

Mr. NARESH KUMAR K · Answer

Acceptor stem

Mr. NARESH KUMAR K · Answer

D-loop

Mr. NARESH KUMAR K · Answer

T\u03a8C loop

Mr. NARESH KUMAR K · Answer

The correct Option is "Anticodon loop"

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