Question

Suppose the following amino acid chain was created based on a student's transcription and translation:
Tyr-Leu-Pro-Met
In the chain, which data show a possible source of error? Explain the error.
I don’t have the student’s DNA/mRNA sequence, but one clear sign of an error in the peptide Tyr–Leu–Pro–Met is the start-site. Translation in cells normally begins at an AUG codon (Met). If the student’s reported peptide begins with Tyr, that means they either
- started translation at the wrong place (they did not start at the first AUG), or
- transcribed/translated the wrong strand or reading frame so that the actual AUG start was missed.
What information did you include in your response? Check all that apply.

The position of Met seems incorrect.

The amino acid sequences of all proteins begin with Met because it is the amino acid that is attached to the anticodon for the AUG start codon.

It looks like the student might have worked in a backward direction for transcription.

Answer 1

Checked items:

- The position of Met seems incorrect. — Yes. I said the peptide starting with Tyr suggests the start site (AUG/Met) was missed.

- The amino acid sequences of all proteins begin with Met because it is the amino acid that is attached to the anticodon for the AUG start codon. — No. I mentioned translation normally begins at AUG (Met), but I did not state that exact claim about anticodons. (Also note: that claim is oversimplified — Met is carried on initiator tRNA, and the initial Met is often removed post‑translationally.)

- It looks like the student might have worked in a backward direction for transcription. — Yes. I suggested they may have used the wrong strand or reading frame, which is consistent with transcribing/reading the sequence in the wrong direction.