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?

Point mutations arise when a single amino acid base is changed. This could cause some differences in the organism or it may not. Manufactured point mutations in model systems such as yeast offer a powerful tool to examine the function of different amino acids in a protein.

There are three types of point mutations

Silent: these mutations have a single residue change but it does not affect the amino acid that is being coded. There is no change to the wild type
Nonsense: will cause a stop or start or gain of start/stop codon.
Mis-sense: will cause a change of amino acid residue. There are two types of mis-sense Conservative and non-conservative. The former will cause a change in amino acid base to one that has similar properties while the former will change to an amino acid of different properties often having different traits than the wild type.