The effect of the following conditions: when the strain is grown in lactose, the strain is grown without lactose, the lacI gene is deleted, and the lac operator is eliminated. Introduction: Lac operon is required for the transport andÂ metabolismÂ ofÂ lactose. In the absence of glucose, it allows for the effective digestion of lactose. They are used in several bacterial-based selection techniques as a reporter gene. LacÂ operon is regarded to be the first genetic regulatory mechanism and also an example of prokaryoticÂ gene regulation.

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Chapter 12, Problem 3TQ

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The effect of the following conditions: when the strain is grown in lactose, the strain is grown without lactose, the lacI gene is deleted, and the lac operator is eliminated.

Introduction:

Lac operon is required for the transport andÂ metabolismÂ ofÂ lactose. In the absence of glucose, it allows for the effective digestion of lactose. They are used in several bacterial-based selection techniques as a reporter gene. LacÂ operon is regarded to be the first genetic regulatory mechanism and also an example of prokaryoticÂ gene regulation.

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A lac operon containing one mutation was cloned into a plasmid, which was introduced by transformation into a bacterium containing a wild-type lac operon. The three genes of the chromosomal operon were rendered noninducible in the presence of the plasmid. (a) What kind of mutation in the plasmid operon could have this effect? (b) Suppose the result of transformation was to cause the three plasmid lac genes to be expressed constitutively, at a high level. What type of plasmid gene mutation could have this result?

1. a) If glucose is not available and lactose is absent from the environment, what is the status of transcription of the lac operon genes? Explain your answer from both an evolutionary perspective and in terms of negative and positive regulation of the operon? b)If glucose is not available, but lactose is available from the environment, what is the status of transcription of the lac operon genes? Explain your answer from both an evolutionary perspective and in terms of negative and positive regulation of the operon? b)

Let’s suppose you have isolated a mutant strain of E. coli in which the lac operon is constitutively expressed. In other words, the operon is turned on in the presence or absence of lactose. One possibility is that the mutation may block the transcription of the lacI gene, thereby preventing the synthesis of lac repressor. A second possibility is that the mutation could alter the sequence of the lac operon in a way that prevents the repressor protein from binding to the operator. How would you distinguish between these two possibilities?