Question

If the DNA codons are CAT CAT CAT, and a guanine base is added at the beginning, then which would result?

Options

• G CAT CAT CAT

• GCA TCA TCA T

• Frameshift mutation

• Both G CAT CAT CAT and GCA TCA TCA T

Answer 1

Both G CAT CAT CAT and GCA TCA TCA T

Explanation:

DNA is read in sets of three nucleotides called codons, which establish a specific “reading frame” for protein synthesis. When a single guanine (G) base is added at the beginning of the sequence, it causes a frameshift mutation, shifting the entire grouping of threes down by one position. Because the machinery still reads the DNA in triplets, the original sequence of CAT CAT CAT is pushed forward, resulting in a new sequence of GCA TCA TCA with a leftover T at the end. This type of mutation is particularly significant because it changes every subsequent codon in the gene, usually leading to the production of a completely different and often non-functional protein.