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Question
How does the operon function in the presence of lactose?
Solution
- Lactose induces the lac operon. The regulatory gene is activated when lactose is added to the bacteria's medium.
- The inducer binds to the repressor protein, rendering it inactive, allowing transcription of the operon.
- Thus, the lac operon is negatively regulated in this case.
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RELATED QUESTIONS
Give one significant contribution to the following scientists:
G. Gamow
Short Answer Question:
Describe the structure of ‘Operon’.
Select the WRONG statement from the following with reference to lac operon.
______ refers to the chemical molecule present in the cytoplasm that inactivates the repressor.
Which of the following is TRUE with reference to Operon?
Match the Column I (Enzymes) with Column II (Functions) and select the correct option.
|
Column I (Enzymes) |
Column II (Functions) |
||
| i. | Permease | P. | Transfers an acetyl group from acetyl CO-A to galactoside |
| ii. | β-galactosi dase | Q. | Entry of lactose into the cell |
| iii. | Transacetylase | R. | Digests lactose into galactose and glucose |
| S. | Aminoacylation |
Lactose operon produces enzymes ______.
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?
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.
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.
