What if a mutation occurred in the human insulin gene and the first codon was changed to CCG? Is
this a silent mutation? Explain how you know.

Yes, this will be a silent mutation.

Explanation:

The mutation which occurred in the human insulin gene where the first codon was changed to CCG will be a silent codon because this will not change the sequence of the amino acid and the amino acids formed will remain the same.

A silent mutation occurs due to base substitutions resulting in a change in the nucleotide that does not impact the amino acid or protein formed once the mRNA is translated. The protein will retains its functional aspects.