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?

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?

Name: A lac operon containing one mutation was cloned into a plasmid, which
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Description: 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 pla

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter14: Gene Regulation

Section: Chapter Questions

Problem 11TYU

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A mutant strain of E. coli has a premature stop mutation in the lacZgene, resulting in a non-functional b-galactosidase. Otherwise, all other parts of the operon are functional. Which component of an F' plasmid will restore normal regulation and function of the lac operon in the resulting partial diploid?
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?
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 mayblock 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 operator in a way that prevents lac repressor from binding to the operator. How would you distinguish between these two possibilities?
If a wild-type (normal, NOTmutated) E. coli strain is grown in a medium: a. without lactose or glucose, how many proteins (and which ones) are bound to the lac operon? b. Without lactose, but with glucose, how many proteins (and which ones) are bound to the lac operon??
What experimental results would indicate that the mutation lacISlacIS is dominant to lacI+lacI+? In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a repressed state in the absence of lactose. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a constitutive state in the absence of the repressor. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in an activated state in the presence of lactose. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a repressed state in the absence of the repressor. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a repressed state in the presence of lactose.
. What is the role of catabolite activator protein (CAP) in the lactose operon of E. coli? it prevents RNA polymerase from binding to the promoter when lactose levels are high it assists RNA polymerase in binding to the promoter when glucose levels are high it prevents RNA polymerase from binding to the promoter when glucose levels are low it assists RNA polymerase in binding to the promoter when glucose levels are low it prevents RNA polymerase from binding to the promoter when lactose levels are low
If glucose levels in the cell are high and 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?
In the presence of lactose and the promoter sequence was mutated such that the RNA polymerase can no longer bind, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the absence of lactose and the lacI repressor gene is mutated such that the repressor protein product can no longer bind to the operator, the structural genes will: [ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the presence of lactose and the lacI repressor gene is mutated such that the repressor protein product can no longer bind to the operator, the structural genes will: [ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"]
The lac operon produces enzymes that allow the bacteria E. coli to metabolize lactose, it is in an inducable operon. When lactose is present, will the repressor protein attach or leave the operon? How would this effect the production of lactose producing enzymes?
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)
In addition to observing similarities to the lac operon, you also notice that this gene is regulated via attenuation, similar to the trp operon. Based on this similarity to this model operon, you could state that ___________. Group of answer choices If a terminator loop forms in the DNA, the expression of the structural genes is halted. The formation of the terminator hairpin followed by a series of Uracil (UUUUUUU) functions similar to Rho-Independent termination to result in the stopping of transcription. The transcription of a leader sequence affects the translation of the structural genes. Never mind – all of these statements are true! Attenuation will be the primary means of transcriptional regulation, with a repressor used as a back up option.
Which of the following describes the lac operon in E. coli when lactose and glucose is present in the culture medium? Select one: a. CAP inactive and RNA polymerase does not completely bind to the promoter of the lac operon and transcription of lactose-metabolizing enzymes decreases. b. CAP is active and RNA polymerase binds completely to the promoter of the lac operon and transcription of lactose-metabolizing enzymes decreases. c. Catabolite activator protein (CAP) inactive and RNA polymerase does not completely bind to the promoter of the lac operon and transcription of lactose-metabolizing enzymes increases. d. CAP is active and RNA polymerase binds completely to the promoter of the lac operon and transcription of lactose-metabolizing enzymes increases.