Topic: Transcription, genetic code, translation, protein biosynthesis· Genetics and Evolution

Under which of the following conditions will there be no change in the reading frame of following mRNA ?5' AACAGCGGUGCUAUU 3'

1. Insertion of G at 5\(^{th}\) position

2. Deletion of G from 5\(^{th}\) position

3. Insertion of A and G at 4\(^{th}\) and 5\(^{th}\) positions respectively

4. Deletion of GGU from 7\(^{th}\), 8\(^{th}\) and 9\(^{th}\) positions

Doubtly Asked 30 Oct 2026 NEET UG 2019 Practice test neet Save WhatsApp Report

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Answer: 4. Deletion of GGU from 7\(^{th}\), 8\(^{th}\) and 9\(^{th}\) positions

Key idea: A change that adds or removes a multiple of 3 bases keeps the reading frame.

Sequence: AAC AGC GGU GCU AUU. Deleting GGU (positions 7 to 9) removes exactly one codon, so all other codons are read the same. The reading frame is unchanged.

Insertion of one base (option 1) or deletion of one base (option 2) causes a frameshift; inserting two bases (option 3) also shifts the frame.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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Under which of the following conditions will there be no change in the reading frame of following mRNA ?5' AACAGCGGUGCUAUU 3'

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