Question

If a codon is mutated, say from GGU to CGU, is the same amino acid specified?

Answer 1

GGU = Glycine
CGU = Alanine
So no

Answer 2

Here's an amino acid chart:
http://www.tritechresearch.com/shop//images/aachart.gif

If you have any questions like this, in the future,
you can look at that chart.

It shows us all of the codons,
and which amino acids those codons will bring in.

Answer 3

Different codons code different amino acids, so no.