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The lac operon consists of a regulation gene and three structural genes. The lactose acts as an inducer. In the presence of an Inducer such as lactose, the repressor is inactivated during the interaction. This allows RNA polymerase access to the promoter and transcription proceeds. The repressor is synthesized which in turn binds with the operator region of the operon and prevents RNA polymerase from transcribing the operon.
The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is____________(1) and glucose is _________(2).
  • a)
    1: Present, 2: Absent
  • b)
    1: Absent, 2: Present
  • c)
    1: More, 2: less
  • d)
    1: repressed, 2: promoted
Correct answer is option 'A'. Can you explain this answer?
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Read the following and answer the question given below:The lac operon...
The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is present and glucose is absent.
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Read the following and answer the question given below:The lac operon...
The lac operon and its regulation

The lac operon is a genetic system found in Escherichia coli (E. coli) bacteria that controls the expression of genes involved in lactose metabolism. It consists of a regulatory gene and three structural genes. The regulatory gene codes for a repressor protein, while the structural genes code for enzymes necessary for lactose metabolism.

Inducer and inactivation of the repressor

The lac operon is regulated by the presence or absence of an inducer molecule, which in this case is lactose. When lactose is present in the environment, it acts as an inducer by binding to the repressor protein. This binding causes a conformational change in the repressor, rendering it inactive.

Access to the promoter and transcription

In the absence of lactose, the repressor protein is active and binds to the operator region of the lac operon. This prevents RNA polymerase, the enzyme responsible for transcribing DNA into RNA, from accessing the promoter region. As a result, transcription of the structural genes is repressed.

However, when lactose is present, it binds to the repressor protein and inactivates it. The inactive repressor can no longer bind to the operator region, allowing RNA polymerase to access the promoter and initiate transcription of the structural genes. This leads to the synthesis of enzymes involved in lactose metabolism.

Expression of the lac operon

The expression of the lac operon is regulated by the presence of lactose and the absence of glucose. Glucose is a preferred carbon source for E. coli, and when it is present in the environment, the lac operon is repressed regardless of the presence of lactose. This is known as catabolite repression.

Therefore, the correct answer to the given question is option A: lactose is present and glucose is absent. In this condition, the repressor is inactivated by the presence of lactose, and RNA polymerase can access the promoter to transcribe the structural genes of the lac operon, allowing for lactose metabolism.

Summary:
- The lac operon consists of a regulatory gene and three structural genes involved in lactose metabolism.
- Lactose acts as an inducer by inactivating the repressor protein.
- In the presence of lactose, the repressor is inactive, allowing RNA polymerase to transcribe the operon.
- The lac operon is expressed only when lactose is present and glucose is absent, due to catabolite repression.
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Read the following and answer the question given below:The lac operon consists of a regulation gene and three structural genes. The lactose acts as an inducer. In the presence of an Inducer such as lactose, the repressor is inactivated during the interaction. This allows RNA polymerase access to the promoter and transcription proceeds. The repressor is synthesized which in turn binds with the operator region of the operon and prevents RNA polymerase from transcribing the operon.The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is____________(1) and glucose is _________(2).a)1: Present, 2: Absentb)1: Absent, 2: Presentc)1: More, 2: lessd)1: repressed, 2: promotedCorrect answer is option 'A'. Can you explain this answer?
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Read the following and answer the question given below:The lac operon consists of a regulation gene and three structural genes. The lactose acts as an inducer. In the presence of an Inducer such as lactose, the repressor is inactivated during the interaction. This allows RNA polymerase access to the promoter and transcription proceeds. The repressor is synthesized which in turn binds with the operator region of the operon and prevents RNA polymerase from transcribing the operon.The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is____________(1) and glucose is _________(2).a)1: Present, 2: Absentb)1: Absent, 2: Presentc)1: More, 2: lessd)1: repressed, 2: promotedCorrect answer is option 'A'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about Read the following and answer the question given below:The lac operon consists of a regulation gene and three structural genes. The lactose acts as an inducer. In the presence of an Inducer such as lactose, the repressor is inactivated during the interaction. This allows RNA polymerase access to the promoter and transcription proceeds. The repressor is synthesized which in turn binds with the operator region of the operon and prevents RNA polymerase from transcribing the operon.The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is____________(1) and glucose is _________(2).a)1: Present, 2: Absentb)1: Absent, 2: Presentc)1: More, 2: lessd)1: repressed, 2: promotedCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Read the following and answer the question given below:The lac operon consists of a regulation gene and three structural genes. The lactose acts as an inducer. In the presence of an Inducer such as lactose, the repressor is inactivated during the interaction. This allows RNA polymerase access to the promoter and transcription proceeds. The repressor is synthesized which in turn binds with the operator region of the operon and prevents RNA polymerase from transcribing the operon.The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is____________(1) and glucose is _________(2).a)1: Present, 2: Absentb)1: Absent, 2: Presentc)1: More, 2: lessd)1: repressed, 2: promotedCorrect answer is option 'A'. Can you explain this answer?.
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