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प्रश्न
A low level of expression of lac operon occurs at all the time. Can you explain the logic behind this phenomena.
उत्तर
In the complete absence of expression of lac operon, permease will not be synthesised which is essential for transport of lactose from medium into the cells. And if lactose cannot be transported into the cell, then it cannot act as inducers hence, cannot relieve the lac operon from its repressed state.
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संबंधित प्रश्न
Short Answer Question:
Describe the structure of ‘Operon’.
A unit of lac-operon which in the absence of lactose, suppresses the activity of operator gene is
Nucleic acids along with (i) and (ii) form the macromolecular fraction of the cell.
Which of the following is TRUE with reference to Operon?
The wild type E. coli cells are growing in normal medium with glucose. They are transferred to a medium containing only lactose as sugar. Which of the following changes takes place?
During expression of an operon, RNA polymerase binds to ______.
Select the two correct statements out of the four (A-D) given below about lac operon.
- Glucose or galactose may bind with the repressor and inactivate it.
- In the absence of lactose, the repressor binds with the operator region.
- The z-gene codes for permease.
- This was elucidated by Francois Jacob and Jacque Mono.
Lac operon consists of ______.
Assertion (A): Regulation of lac operon by a repressor is referred to as negative regulation.
Reason (R): Lac operon is under the control of positive regulation as well.
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.
