Question

Which of the following is a wrong statement regarding the conventional determination of open reading frames?

(a) Without the use of specialized programs, prokaryotic gene identification can rely on manual determination of ORFs and major signals related to prokaryotic genes

(b) Prokaryotic DNA is first subject to conceptual translation in all six possible frames, two frames forward and four frames reverse

(c) A stop codon occurs in about every twenty codons by chance in a noncoding region

(d) Prokaryotic DNA is first subject to conceptual translation in all six possible frames, three frames forward and three frames reverse

I had been asked this question during a job interview.

My enquiry is from Gene Prediction in Prokaryotes topic in division Gene and Promoter Prediction of Bioinformatics

Answer 1

Right option is (b) Prokaryotic DNA is first subject to conceptual translation in all six possible frames, two frames forward and four frames reverse

Easy explanation: Prokaryotic DNA is first subject to conceptual translation in all six possible frames, three frames forward and three frames reverse. Because a stop codon occurs in about every twenty codons by chance in a noncoding region, a frame longer than thirty codons without interruption by stop codons is suggestive of a gene coding region, although the threshold for an ORF is normally set even higher at fifty or sixty codons.