Frame shift mutation does not effect complete amino acid sequence if it occurs in multiple of ?

**Core Concept:**
A frame shift mutation is a type of genetic mutation that causes a change in the reading frame of a gene, leading to an abnormal amino acid sequence and potentially resulting in a disease. Complete amino acid sequence refers to the correct reading frame of the gene, where each amino acid is correctly incorporated in the polypeptide chain.

**Why the Correct Answer is Right:**
The correct answer is "D." A frame shift mutation does not affect the complete amino acid sequence if it occurs in a multiple of three nucleotides. In the context of DNA, this corresponds to a multiple of three nucleotides because the genetic code is triplet-based. Each amino acid is coded by three nucleotides, which are known as codons. When a frame shift mutation occurs in a multiple of three nucleotides, it does not alter the reading frame, and thus the amino acid sequence remains unaffected.

**Why Each Wrong Option is Incorrect:**

A. A frame shift mutation occurring in a multiple of two nucleotides would disrupt the reading frame, causing a significant impact on the amino acid sequence.
B. A frame shift mutation occurring in a single nucleotide would disrupt the reading frame, also affecting the amino acid sequence.
C. A frame shift mutation occurring in a multiple of four nucleotides would disrupt the reading frame, leading to a significant impact on the amino acid sequence.

**Clinical Pearl / High-Yield Fact:**
A frame shift mutation causing a multiple of three-nucleotide change can be tolerated by cells because of a process known as readthrough transcription. This process allows the ribosome to skip the premature stop codon and continue reading the gene, preventing a complete loss of protein function. However, if the mutation leads to a multiple of four nucleotide change, the process of readthrough transcription is less efficient, potentially causing a significant impact on the amino acid sequence and disrupting the protein function. This is why option C is incorrect.

**Correct Answer:** D. A frame shift mutation occurring in a multiple of three nucleotides does not affect the complete amino acid sequence.