Final answer:
There are six possible reading frames for the ORF of the mRNA at the YFG locus, three on one strand and three on the complementary strand, which are crucial for accurate protein synthesis during translation.
Step-by-step explanation:
When determining the number of possible reading frames for the open reading frame (ORF) of the mRNA at the YFG locus, we must consider that on any single strand of DNA, there can be three different reading frames depending on the starting point. The same applies to the complementary strand, resulting in six possible reading frames total for any segment of DNA, including the YFG locus. These reading frames are essential for the translation process where ribosomes read mRNA sequences in sets of three nucleotides (codons) to synthesize proteins. Any insertions or deletions can shift these frames, known as frameshift mutations, profoundly affecting the resulting protein. An mRNA with an altered reading frame may produce a nonfunctional protein due to these changes.