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#frameshift mutation

6 public questions tagged with this topic.

BOTANY

Which type of mutation results in the addition or deletion of a nucleotide, shifting the reading frame?

A frameshift mutation occurs when nucleotide insertions or deletions shift the genetic reading frame. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Botany section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Botany portion (Latest NCERT Textbooks for Academic Session 2026-27 -

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Mutation and Mutagenesis

Insertion or deletion of 1 bp causes

Genetic code reads non-overlapping triplets, so addition or deletion of base pairs that is not multiple of three shifts downstream reading frame. Single base insertion or deletion in coding exon moves ribosome entry, altering every subsequent codon and usually introducing premature stop codon downstream leading to truncated protein. This frameshift drastically changes primary structure and often eliminates function, causing severe phenotypes. In contrast, three-base indels preserve frame, illustrating why 1-bp indels represent classic frameshift mutational mechanism. This principle illustrates essential molecular mechanisms governing replication fidelity and mutation fixation relevant for exam interpretation.

Ref: Watson et al., Molecular Biology of the Gene, 7th ed., Chapter 11: Frameshift by Single Base Indels

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