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Select the two correct statements out of the four (a–d) given below about lac operon.
(a) Glucose or galactose may bind with the repressor and inactivate it
(b) In the absence of lactose the repressor binds with the operator region
(c) The z-gene codes for permease
(d) This was elucidated by Francois Jacob and Jacque Monod
The correct statements are
(a) Glucose or galactose may bind with the repressor and inactivate it
(b) In the absence of lactose the repressor binds with the operator region
(c) The z-gene codes for permease
(d) This was elucidated by Francois Jacob and Jacque Monod
The correct statements are
A
(a) and (b)
B
(b) and (c)
C
(a) and (c)
D
(b) and (d)
Detailed Solution
(a) is wrong: the inducer of the lac operon is lactose (allolactose); it binds to the repressor and inactivates it. Glucose and galactose cannot act as inducers.
(b) is correct: in the absence of the inducer (lactose), the repressor protein made by the i gene binds to the operator region and prevents RNA polymerase from transcribing the operon.
(c) is wrong: the z gene codes for β-galactosidase; permease is coded by the y gene and transacetylase by the a gene.
(d) is correct: the lac operon was elucidated by the geneticist Francois Jacob and the biochemist Jacque Monod.
Hence the correct statements are (b) and (d).
(b) is correct: in the absence of the inducer (lactose), the repressor protein made by the i gene binds to the operator region and prevents RNA polymerase from transcribing the operon.
(c) is wrong: the z gene codes for β-galactosidase; permease is coded by the y gene and transacetylase by the a gene.
(d) is correct: the lac operon was elucidated by the geneticist Francois Jacob and the biochemist Jacque Monod.
Hence the correct statements are (b) and (d).