Why is it unwise to use only one particular DNA sequence as a probe for isolating a gene?

the AA sequence is known, and you find a sequence in particular that can encode for the protein. Why is it not a good idea to only use this sequence as the probe for isolating the gene responsible for encoding the protein of interest from a DNA library?|||Because there is more than one way to go from a protein sequence to a DNA sequence. There are several codons, the sequence of triplets bases in the DNA code, that can code for different amino acids. That is why the DNA code is referred to as degenerate. Using a codon bias table can be helpful, but in general you need to take into account the other possible ways of coding for the particular protein framgment of interest.|||the two strands are complimentary