A frameshift mutation occurs when the number of nucleotides inserted or deleted is not a multiple of three, thus shifting the reading frame of the genetic code. In the case of a deletion, if one or two nucleotides are removed, it will alter the subsequent codons.
Given the original DNA strand: ATG AAG TTT GGC TAA
We need to find an option where the deletion of nucleotides causes a shift in the reading frame.
Among the options provided, the fourth option is: ATG AAG TTG GCT AA Here, the codon "TTT" is deleted (which consists of three nucleotides), but this option does not represent a frameshift; instead, it keeps the reading frame because three nucleotides were removed.
None of the other provided options indicate a frameshift mutation caused by a deletion.
However, if we analyze:
- ATG AAG AAG TTT GGC TAA - This does not have a deletion; it adds an AAG.
- ATG AAG TTT GGC CGC ATA A - This adds "CGC ATA A," which also does not indicate a simple deletion.
- ATG AAG TTT GGC - No deletion shown.
Since the option ATG AAG TTG GCT AA effectively keeps and shifts the reading frame after a codon deletion, it’s the only one that satisfies the criteria for illustrating a frameshift mutation.
It would be best to prioritize finding a combination where a single nucleotide or two are deleted causing a frameshift.
However, referring specifically, ATG AAG TTG GCT AA is the closest option that signifies a shift, assuming that deletion occurred but does not strictly meet the 'frameshift' delineation since there is an understanding of what constitutes authentic shifts needing careful reading.
In essence, ATG AAG TTG GCT AA is considered the ‘best option for demonstrating a frameshift caused by the removal of “TTT” ignoring the standard codon triplet criteria for frameshifts in addition.
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