
Concept explainers
a.
To determine:
The reason behind the appearance of white color of luxR/lacZ colonies in the absence of autoinducer.
Introduction:
In an experiment to understand the molecular mechanism of quorum sensing, the use of two transcriptional fusion reporter genes was involved each having the 9 kb fragment of Vibrio fischeri DNA.
b.
To determine:
The reason behind the appearance of white color of luxICDABE/lacZ colonies in the absence of autoinducer.
Introduction:
In a reporter known as luxICDABE/lacZ, the luxICDABE operon regulatory sequences drive lacZ expression. It means that the structural genes of the operon are replaced by the lacZ coding sequences.
c.
To determine:
The reason behind the appearance of white color of luxR/lacZ colonies in the presence of autoinducer.
Introduction:
In the reporter known as luxR/lacZ, the luxR regulatory region drives the transcription of lacZ. It means that the luxR coding sequences are replaced by the lacZ.
d.
To determine:
The reason behind the appearance of blue colored luxICDABE/lacZ colonies in the presence of autoinducer and the time-dependency of the reaction.
Introduction:
The E.coli that contains either of the reporter (luxR/lacZ or luxICDABE/lacZ) has white colonies. When the purified autoinducer is added to the media, the luxR/lacZ colonies remain white but the luxICDABE/lacZ colonies turn blue over time.
e.
To determine:
The inference that can be made out about the transcription of the luxR gene from the given results.
Introduction:
The regulatory region of luxR drives the transcription of the lacZ gene. It indicates that the coding sequence of luxR is replaced by the coding sequence of lacZ.

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Chapter 16 Solutions
Genetics: From Genes To Genomes (6th International Edition)
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