The Question is from neet-botany , and it was created by the author Mr. NARESH KUMAR K

Question

A mutation in a eukaryotic gene results in the production of a truncated protein lacking its C-terminal region.  Analysis reveals a mutation within an intron of the gene.  Which of the following is the MOST likely explanation?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: Eukaryotic gene expression and splicing
 **Related Topics**: Introns, exons, splicing enhancers, spliceosomes, premature termination codons, polyadenylation
 **Prerequisites**: Understanding of basic molecular biology, including transcription, translation, and RNA processing.
## SOLUTION PATHWAY
**Given Information**:
  * A mutation in a eukaryotic gene's intron.
  * Results in a truncated protein lacking the C-terminal region.
  * The mutation is within an intron, not an exon.
**Method & Steps**:
 1. Consider the role of introns in eukaryotic gene expression. Introns are non-coding sequences within a gene that are removed during RNA processing (splicing).
  Reasoning: The mutation is in an intron, so it directly affects splicing.
  Formula/Rule: None directly applicable, this is a conceptual understanding question.
 2. Analyze the effect of the mutation on the final protein product. A truncated protein suggests that some part of the coding sequence (exon) is missing from the mature mRNA.
  Working: The C-terminal region is missing. This indicates that a portion of the mRNA corresponding to the 3' end of the gene is absent.
  Key Point:  Intron mutations primarily affect splicing, not translation directly.
 3. Evaluate the given options. Option A is the most likely explanation because a mutation in a splicing enhancer sequence could prevent the correct recognition and removal of an intron, leading to exon skipping (inclusion of the intron or exclusion of an exon).
  Result: Option A is the most likely explanation.
  Verification: The other options are less likely because the mutation is in an intron.  A new promoter in an intron would likely lead to an additional transcript, not a truncated protein.  A mutation in the polyadenylation signal would affect mRNA termination, but not necessarily result in a truncated protein. A premature stop codon within the intron would not be translated.
 ## OPTION ANALYSIS
A ✓: The mutation disrupted a splicing enhancer sequence, leading to exon skipping. This explains the truncated protein.  The splicing machinery fails to remove the affected exon, or incorrectly joins exons, resulting in a truncated protein.
B :x: The mutation created a new promoter within the intron. This would likely lead to transcription of the intron, resulting in a longer mRNA, not a shorter one.
C :x: The mutation disrupted the polyadenylation signal, preventing proper termination.  This would affect the 3' end of the mRNA but wouldn't necessarily result in a truncated protein. The protein might be full length but unstable.
D :x: The mutation created a premature stop codon within the intron. Introns are not translated into proteins, therefore a premature stop codon within an intron would not be expressed.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Assuming the mutation directly affects the coding sequence: The key is understanding that intron mutations primarily affect splicing.
  2.Overlooking the role of splicing enhancers: Splicing enhancers are crucial for proper spliceosome assembly and function.
 **Quick Tips**:
  1.Focus on the effect of the mutation on splicing and the resulting mRNA.
  2.Remember that introns are removed during RNA processing.

Mr. NARESH KUMAR K · Answer

The correct Option is "The mutation disrupted a splicing enhancer sequence, leading to exon skipping."

Mr. NARESH KUMAR K · Answer

The mutation created a new promoter within the intron.

Mr. NARESH KUMAR K · Answer

The mutation disrupted the polyadenylation signal, preventing proper termination.

Mr. NARESH KUMAR K · Answer

The mutation created a premature stop codon within the intron.

NEET Botany MCQs

Select Chapter

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