Question

You modify your gene DNA sequence by introducing an attenuator within the transcribed region. You isolate the labeled gene product and perform SDS PAGE. You observe two bands one higher and another slightly lower. Which of this band corresponds to properly modified sequence?

(a) Higher

(b) Lower

(c) Both the bands as they show differently folded protein

(d) This is an experimental artifact

This question was posed to me in homework.

This question is from Transcription in Prokaryotes : Termination in section Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Correct answer is (b) Lower

Easy explanation: An attenuator will lead to premature transcription termination. This will result in a truncated protein that will migrate faster in the gel and form the lower band. Protein folding doesn’t affect its migration in SDS page.