Genetic Code and Codon Translation (1B) Practice Test

In a bacterial expression study, a single-base substitution changed codon 12 in an enzyme mRNA from 5'-GAA-3' to 5'-GAG-3'. Protein yield and enzymatic activity were unchanged across replicates. A lab note lists the relevant code: GAA → Glu, GAG → Glu. Based on the information, which conclusion is most consistent with codon redundancy during translation?

A mitochondrial gene is sequenced from a patient sample. A variant changes a codon in the middle of the open reading frame from 5'-UAU-3' to 5'-UAC-3'. The peptide sequence around this site is unchanged by mass spectrometry. A note in the sequencing report states: UAU → Tyr; UAC → Tyr. Based on the information, which conclusion is most consistent with codon redundancy?