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The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made:
A. cAMP levels are high.
B. repressor is bound to the allolactose
C. cap is interacting with RNA polymerase
Based on the observations above, which of the following conclusions is most appropriate?
- a)Galactose is absent and lactose are present.
- b)Glucose is present and lactose is absent.
- c)Both are present
- d)Glucose is absent and lactose is present.
Correct answer is option 'D'. Can you explain this answer?
Verified Answer
The lac operon in E coli is controlled by both the lac repressor and t...
Concept:
- An operon is a functional piece of DNA that houses a collection of genes that are all regulated by the same promoter.
- In addition to regulatory genes, the lac operon in E. coli also comprises three structural genes.
- The structural genes are lacZ, lacY, and lacA.
- LacZ encodes the enzyme -galactosidase, lacY encodes lactose permease, and lacA encodes lactose transacetylase.
Explanation:
Fig 1: Lac Operon in E.coli
- E. coli requires galactosidase and lactose permease to effectively use lactose for growth; of these enzymes, -galactosidase transforms lactose into glucose and galactose.
- The lac operon's regulatory genes include lacP (promoter), which is simply the RNA polymerase-binding site, lacO (operator), which is the repressor-binding site, and lad (lac repressor), which has its own promoter and terminator sequences.
- The transcription of the lac operon is controlled by the lac repressor, which is created from the lacl gene.
- To prevent the lac operator's transcription, the repressor binds to it.
- On the other side, the inducer, in this case lactose, prevents the development of the repressor-operator complex.
- In other words, the repressor experiences conformational changes that decrease its binding affinity for the lac operator when lactose is present in the system.
- The repressor consequently separates from the operon and makes it easier to start gene transcription.
- Therefore, these genes are not translated when E. coli grows on sources other than lactose, such as carbon-based sources, resulting in a very low concentration of these enzymes in the cell.
- Contrarily, the synthesis of these enzymes is markedly increased by the presence of lactose.
- Transcription of lac operon genes does not begin until all glucose molecules have been consumed in cells that contain both glucose and lactose.
- A glucose catabolite, a byproduct of the breakdown of glucose, hinders the conversion of ATP into cAMP, a necessary step for the start of lac operon transcription, when cellular glucose levels are high.
- As a result, by altering the cellular concentration of cAMP, glucose metabolism also controls the expression of lac operon genes.
hence the correct answer is option 4
Most Upvoted Answer
The lac operon in E coli is controlled by both the lac repressor and t...
Explanation:
High cAMP levels:
- High cAMP levels indicate that glucose levels are low in the cell, as cAMP levels increase when glucose is scarce.
- This leads to the activation of CAP, which interacts with RNA polymerase to promote transcription.
Repressor bound to allolactose:
- When the repressor is bound to allolactose, it is unable to bind to the operator region of the lac operon.
- This allows RNA polymerase to transcribe the genes involved in lactose metabolism.
CAP interacting with RNA polymerase:
- CAP interacts with RNA polymerase to enhance transcription of the lac operon genes when glucose is low and cAMP levels are high.
- This helps E. coli cells to utilize lactose as an alternative energy source.
Conclusion:
- Based on the observations provided, we can conclude that glucose is absent (indicated by high cAMP levels) and lactose is present (repressor bound to allolactose and CAP interacting with RNA polymerase).
- Therefore, the most appropriate conclusion is that glucose is absent and lactose is present in the experimental setup.
High cAMP levels:
- High cAMP levels indicate that glucose levels are low in the cell, as cAMP levels increase when glucose is scarce.
- This leads to the activation of CAP, which interacts with RNA polymerase to promote transcription.
Repressor bound to allolactose:
- When the repressor is bound to allolactose, it is unable to bind to the operator region of the lac operon.
- This allows RNA polymerase to transcribe the genes involved in lactose metabolism.
CAP interacting with RNA polymerase:
- CAP interacts with RNA polymerase to enhance transcription of the lac operon genes when glucose is low and cAMP levels are high.
- This helps E. coli cells to utilize lactose as an alternative energy source.
Conclusion:
- Based on the observations provided, we can conclude that glucose is absent (indicated by high cAMP levels) and lactose is present (repressor bound to allolactose and CAP interacting with RNA polymerase).
- Therefore, the most appropriate conclusion is that glucose is absent and lactose is present in the experimental setup.
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The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer?
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The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer? for Software Development 2025 is part of Software Development preparation. The Question and answers have been prepared according to the Software Development exam syllabus. Information about The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Software Development 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer?.
The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer? for Software Development 2025 is part of Software Development preparation. The Question and answers have been prepared according to the Software Development exam syllabus. Information about The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Software Development 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer?.
Solutions for The lac operon in E coli is controlled by both the lac repressor and the catabolite activation protein CAP. In an experiment with Lac Operon, the following observations were made: A. cAMP levels are high. B. repressor is bound to the allolactose C. cap is interacting with RNA polymerase Based on the observations above, which of the following conclusions is most appropriate?a)Galactose is absent and lactose are present.b)Glucose is present and lactose is absent.c)Both are presentd)Glucose is absent and lactose is present.Correct answer is option 'D'. Can you explain this answer? in English & in Hindi are available as part of our courses for Software Development.
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