Explanation

In mitochondrial DNA, the codon AGG typically codes for a stop codon. 

Standard genetic code:

• In the standard genetic code, AGG codes for the amino acid arginine. 

Mitochondrial code deviation:

• However, mitochondrial DNA often uses a slightly different genetic code.
• In many mitochondrial genomes, including those of vertebrates, the codons AGA and AGG are reassigned as stop codons, meaning they signal the end of protein translation.