In constructing an oligonucleotide probe based on information from a protein's sequence, one often chooses, if possible, regions of a sequence containing tryptophan or methionine residues. Why?

As the two amino acids have only one codon, the oligonucleotide probe will have a greater specificity for the DNA which Correct precisely the sequence of the probe that matches that of the target sequence, the fewer false positives one will encounter.

Explanation:

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.