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प्रश्न
Explain the role of Lactose as an inducer in Lac-operon.
उत्तर
- A few molecules of lactose enter into the cell by an enzyme permease.
- A small amount of this enzyme is present even when the operon is switched off.
- A few molecules of lactose, act as an inducer and bind to the repressor.
- This repressor–inducer complex fails to join with the operator gene, which is then turned on.
- Structural genes produce all enzymes. Thus, lactose acts as an inducer of its own breakdown.
- When the inducer level falls, the operator is blocked again by a repressor. So structural genes are repressed/inactivated again. This is negative feedback.
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संबंधित प्रश्न
Give one significant contribution to the following scientists:
G. Gamow
What is meant by an operon?
Identify the event that would occur in 'lac operon' of E. coli when the growth medium has high concentration of lactose.
Which of the following is the function of promoter in lactose operon of Escherichia coli?
In lac operon concept of gene expression, allolactose acts as, ____________.
The sequence of structural genes in lac operon is ______.
Lac operon consists of ______.
Which of the following is required as an inducer(s) for the expression of lac operon?
In lac operon system, gene - z codes for ______.
Study the schematic representation of the genes involved in the lac operon given below and answer the questions that follow:
| p | i | p | o | z | y | a |
(a) The active site of enzyme permease present in the cell membrane of a bacterium has been blocked by an inhibitor, how will it affect the lac operon?
(b) The protein produced by the i gene has become abnormal due to unknown reasons. Explain its impact on lactose metabolism stating the reason.
(c) If the nutrient medium for the bacteria contains only galactose; will operon be expressed? Justify your answer.
