Explanation:
An environmental agent, which triggers transcription from an operon, is a inducer. The inducer in the lac operon is allolactose. If lactose is present in the medium, then a small amount of it will be converted to allolactose by a few molecules of \(\beta\)-galactosidase that are present in the cell.
546.
(A)

(B)

(C)

Identify \(A, B\) and \(C\)
(a) (A) Elongation, (B) Termination,
(C) Initiation
(b) (A) Initiation, (B) Termination,
(C) Elongation
(c) (A) Initiation, (B) Elongation,
(C) Termination
(d) (A) Termination, (B) Elongation,
(C) Initiation
Ans. (b)
Exp: (A) A sigma factor is a protein needed for initiation of transcription in bacteria. It is a bacterial transcription initiation factor that enables specific binding of RNA polymerase (RNA Pol.) to gene promoters.
(B) Rho-factor is a prokaryotic protein involved in the termination of transcription.
(C) Translation elongation is simply the ribosome travelling down the message, reading codons and bringing in the proper aminoacyl tRNA's to translate the message out to protein.