Codons that encode for amino acids

Question

when the amino acid sequences of insulin isolated from different organisms were determined, some differences were noted. alanine was substituted for threoninem serine was substituted for glycine, and valine was substituted for isoleucine at corresponding positions in the protein. list the single changes that could occur in codons to produce these changes. do you expect these changes to significantly affect the functionof the protein?

you may need this to answer the question

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Answer 1

Look up all the different triplets that code for alanine, and all the triplets that code for threonine. Then see if there is any alanine triplet that can be  converted to a threonione triplet by a single change.

Likewise for all the other changes.

All these variations have survived.  What does that tell you about whether or not they make a big difference?