Final answer:
Changing the codon sequence from TCT to TCC results in a missense mutation, altering the encoded amino acid from serine to serine. The overall functionality of the protein may not be significantly affected.
Step-by-step explanation:
When a codon sequence is changed from TCT to TCC, it results in a missense mutation. This means that the amino acid encoded by the codon will be changed. In this case, the change is from serine (Ser) to serine (Ser), which is a synonymous substitution. While the protein sequence will be slightly altered, the overall functionality of the protein may not be significantly affected.