The codon UUA was changed to AUA. How would that base change impact the protein being translated?

DNA directs protein synthesis by the processes of transcription followed by translation. When messenger RNA copies the DNA code in a process called transcription, each triplet or codon signifies which amino acid will be added into a growing polypeptide. 

The mRNA attaches to a ribosome which is the site of translation. Transfer RNA molecules bring the correct amino acids to the growing polypeptide chain based on each triplet or codon in the mRNA. They transfer...

DNA directs protein synthesis by the processes of transcription followed by translation. When messenger RNA copies the DNA code in a process called transcription, each triplet or codon signifies which amino acid will be added into a growing polypeptide. 

The mRNA attaches to a ribosome which is the site of translation. Transfer RNA molecules bring the correct amino acids to the growing polypeptide chain based on each triplet or codon in the mRNA. They transfer these amino acids from the cytoplasmic pool which contains all 20 amino acids. On one end of tRNA is the amino acid it carries and on the other end is a triplet called an anticodon which base pairs to the codon on mRNA while it delivers its amino acid. Ribosomes facilitate the joining of the tRNA anticodons with the mRNA codons during protein synthesis.

There is a start codon AUG and the tRNA brings into the first position the amino acid methionine. At the end of the mRNA transcript is a stop codon or termination sequence, which is one of the following triplets: UAA, UAG or UGA. This causes translation to stop and the polypeptide to detach from the ribosome. The translation assembly will break down. The polypeptide will then fold into a protein.

The codon UAA is a stop codon. If a mutation changed it to AUA, this would result in the addition of the amino acid isoleucine to be added to the polypeptide chain.  The stop codon would no longer be present in the correct position. This type of mutation will result in a protein that is longer than normal. Translation won't cease until another termination codon is found. The new protein will be longer than normal and may not function properly or at all.