If a base is copied more than once during DNA replication, what effect may this have on the resulting protein?

If a base is copied more than once during DNA replication, what effect may this have on the resulting protein?

• A. Changes in base sequence
• B. No effect
• C. Stops transcription entirely
• D. Only affects non-coding regions

Answer: (A)

A base being copied more than once introduces an extra nucleotide into the DNA sequence, altering the base sequence. That change is carried into the mRNA during transcription, so the codons that specify amino acids in the protein are different. Because the genetic code translates codons into amino acids, the protein's amino acid sequence is likely altered, which can change its structure and function. An insertion like this often shifts the reading frame, causing many downstream codons to be read incorrectly and frequently producing a nonfunctional or truncated protein. While some rare cases might be silent if the insertion falls in a way that doesn’t change the encoded amino acids, the typical outcome is a changed protein due to the altered base sequence.

A base being copied more than once introduces an extra nucleotide into the DNA sequence, altering the base sequence. That change is carried into the mRNA during transcription, so the codons that specify amino acids in the protein are different. Because the genetic code translates codons into amino acids, the protein's amino acid sequence is likely altered, which can change its structure and function. An insertion like this often shifts the reading frame, causing many downstream codons to be read incorrectly and frequently producing a nonfunctional or truncated protein. While some rare cases might be silent if the insertion falls in a way that doesn’t change the encoded amino acids, the typical outcome is a changed protein due to the altered base sequence.