a hypothetical ncrna is shown below. this ncrna is known to exert its function by binding to a protein and altering its structure. the underlined segment is the only part of the ncrna that physically contacts the protein. a mutation that disrupts the function of this ncrna is identified. surprisingly, the underlined sequence is normal in the mutant, but the boxed sequence in the dna, taa is changed to act. what is the most likely reason the ncrna no longer functions?