GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
irreversible binding of the repressor to the operator.
|
|
|
complete inhibition of transcription of the structural gene controlled by that regulator.
|
|
|
inactivation of RNA polymerase by alteration of its active site.
|
|
|
continuous transcription of the structural gene controlled by that regulator.
|
Detailed explanation-1: -A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in: a.) continuous transcription of the structural gene controlled by that regulator.
Detailed explanation-2: -The correct answer option is “continuous transcription of the structural gene controlled by that regulator”. A repressible operon is a form of an operon in which the presence of a certain substance inhibits gene transcription. In E.
Detailed explanation-3: -In lac operon of E. coli, the repressor is synthesised constitutively from the i gene which binds to the operator region of the operon and prevents RNA polymerase from transcribing the structural genes. In the presence of an inducer (lactose or allolactose), the repressor is inactivated by interaction with the inducer.
Detailed explanation-4: -coli tryptophan operon affect transcription of the trp genes? Transcription of the operon would occur even if tryptophan were abundant. Removal of the operator, therefore, would remove any hindrance to transcriptional control, and the operon would be expressed under all conditions.
Detailed explanation-5: -An increasing number of the identified disease-related mutations occur in gene regulatory sequences. These regulatory mutations can disrupt transcription factor binding sites or create new ones.