Question

Granting agency requires a certain level of accuracy in case of errors. Which of the given statements is untrue regarding it?

(a) In other laboratories, such as those performing a single-attempt sequencing of ESTs, the error rate may be much higher, approximately 1 in 100, including incorrectly identified bases and inserted or deleted bases

(b) Incorrect bases always translate to the right amino acid

(c) Base insertions/deletions will cause frame-shifts in the sequence

(d) Making alignment with a protein sequence becomes difficult because of frameshifts

I have been asked this question in an international level competition.

Question is taken from Sequencing cDNA Libraries of Expressed Genes, Submission of Sequences to the Databases topic in division Collecting & Storing Sequences in Laboratory of Bioinformatics

Answer 1

The untrue statement is:

(b) Incorrect bases always translate to the right amino acid

This statement is untrue because incorrect bases in a sequence do not always translate to the correct amino acid. The amino acid sequence is determined by the codons in the mRNA, and if the sequence contains errors (incorrect bases), it can lead to incorrect amino acids being encoded, potentially causing mutations, dysfunctions, or disease.

Here's why the other statements are true:

• (a) Error rates in some sequencing methods, like single-attempt sequencing of ESTs, can indeed be high, including incorrect bases and insertions or deletions.
• (c) Base insertions or deletions do cause frame-shifts, which alter the reading frame of the gene and can lead to different, often nonfunctional, proteins.
• (d) Aligning sequences with proteins becomes difficult due to frameshifts, as the alignment may not properly match up the codons with the correct amino acids.

So, the correct answer is (b).