NEET 2019 · Class 12

Molecular Basis of Inheritance

Under which of the following conditions will there be no change in the reading frame of following mRNA? 5'AACAGCGGUGCUAUU3'

  1. (A)Deletion of G from 5th position
  2. (B)Insertion of A and G at 4th and 5th positions respectively
  3. (C)Deletion of GGU from 7th, 8th and 9th positions
  4. (D)Insertion of G at 5th position

The NCERT line that answers it

Verbatim line

Insertion or deletion of three or its multiple bases insert or delete in one or multiple codon hence one or multiple amino acids, and reading frame remains unaltered from that point onwards.

Chapter
Molecular Basis of Inheritance
Section
5.6.1 Mutations and Genetic Code
Page
19
Words matched
32 of 32

The answer appears as a continuous sentence in NCERT. This is that sentence.

How this line gives the answer

6667, emb=1.0, combined=0.8667). Verified: high — The span explicitly states that deletion of three bases (or multiples thereof) leaves the reading frame unaltered, which directly matches option C's deletion of three nucleotides (GGU) and distinguishes it from the other options involving single or double base changes.

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