If the last cytosine is replaced by a guanine, the last amino acid will become tryptophan instead of cysteine.
UUG AUC CAA UGC.
UUG AUC CAA UGG.
This type of mutation that changes the amino acid is called missense mutation.
In humans, mutations of this type are responsible for diseases such as sickle cell disease. In plants, false sense mutations control, for example, the thickness of the hull of the oil palm fruit.