Only one amino acid was altered in each mutant TrpA protein. A single amino acid in the TrpA protein could be altered in different ways in different trpA- mutants. Three of the amino acid changes were alterations of an original Gly amino acid. The sites of the point mutations in the different trpA- mutants correlated in a linear manner with the altered amino acids in the different mutant TrpA proteins. More trpA- mutations occurred at the 3' end of the coding region than in the 5' end. Some of the trpA- mutants were nonsense mutations and others were missense mutations. True or false?