Gene Mutations Alter DNA Codons, Not Transcription or Translation Processes

Steps:

• Gene mutations change DNA base sequences, affecting mRNA codons during transcription and protein synthesis.
• Evaluate statement 1: Transcription copies DNA to mRNA; no nucleotides are added to DNA during this process—mutations occur via DNA replication errors.
• Evaluate statement 2: A mutation in the gene's DNA bases alters the corresponding mRNA codon, leading to incorrect tRNA binding and a faulty amino acid in the protein.
• Evaluate statement 3: Anticodons on tRNA are fixed and not altered during translation; mutations do not change tRNA sequences.

Why D is correct:

• Statement 2 aligns with the central dogma: DNA mutations change codon sequences in mRNA, causing mistranslation and non-functional proteins.

Why the others are wrong:

• A: Includes statements 1 and 3, which misplace mutation events outside DNA.
• B: Includes statement 1, which confuses transcription with DNA alteration.
• C: Includes statement 3, which incorrectly attributes changes to tRNA during translation.

Final answer: D