Q. No.What does "lac" refer to in what we call the lac operon:
1. Lactose
2. Lactase
3. Lac insect
4. The number 1,00,000
Subtopic: Gene Regulation: Lac Operon |
96%
Level 1: 80%+
AIPMT - 2003
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In the lac operon of E. coli, what happens when lactose is present?
| 1. | Repressor binds to the operator, blocking transcription. |
| 2. | Lactose binds to the repressor, inactivating it and allowing transcription. |
| 3. | RNA polymerase cannot bind to the promoter. |
| 4. | The operon is permanently switched off. |
Subtopic: Gene Regulation: Lac Operon |
90%
Level 1: 80%+
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Match List-I with List- II
Choose the correct answer from the options given below:
| List-I | List-II | ||
| (a) | In lac operon i gene codes for | (i) | transacetylase |
| (b) | In lac operon z gene codes for | (ii) | permease |
| (c) | In lac operon y gene codes for | (iii) | \(\beta-\)galactosidase |
| (d) | In lac operon a gene codes for | (iv) | Repressor |
| (a) | (b) | (c) | (d) | |
| 1. | (iii) | (ii) | (i) | (iv) |
| 2. | (iv) | (iii) | (ii) | (i) |
| 3. | (iv) | (i) | (iii) | (ii) |
| 4. | (iii) | (i) | (iv) | (ii) |
Subtopic: Gene Regulation: Lac Operon |
93%
Level 1: 80%+
NEET - 2022
Hints
Which of the following enzyme is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units galactose and glucose in the Lac operon?
| 1. | Beta-galactosidase | 2. | Permease |
| 3. | Transacetylase | 4. | Tyrosinase |
Subtopic: Gene Regulation: Lac Operon |
91%
Level 1: 80%+
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All of the following are part of an operon except:
1. an operator
2. structural genes
3. a promoter
4. an enhancer
Subtopic: Gene Regulation: Lac Operon |
91%
Level 1: 80%+
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Which of the following is required as inducer(s) for the expression of Lac operon?
1. Galactose
2. Lactose
3. Lactose and galactose
4. Glucose
1. Galactose
2. Lactose
3. Lactose and galactose
4. Glucose
Subtopic: Gene Regulation: Lac Operon |
88%
Level 1: 80%+
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The lac operon in E. coli is activated when:
| 1. | Glucose levels are high, and lactose is absent. |
| 2. | Glucose levels are low, and lactose is present. |
| 3. | cAMP levels are low, and lactose is absent. |
| 4. | Both glucose and lactose are present in high amounts. |
Subtopic: Gene Regulation: Lac Operon |
81%
Level 1: 80%+
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The lac Operon consists of:
| 1. | One regulatory gene and three structural genes |
| 2. | Two regulatory genes and two structural genes |
| 3. | Three regulatory genes and three structure genes |
| 4. | Four regulatory genes only |
Subtopic: Gene Regulation: Lac Operon |
88%
Level 1: 80%+
AIPMT - 2010
Hints
Which of the following best describes a regulatory gene?
| 1. | A gene that encodes enzymes for cellular respiration |
| 2. | A gene that does not have an operator |
| 3. | A gene that is transcribed but not translated |
| 4. | A gene that codes for proteins involved in controlling the expression of other genes |
Subtopic: Gene Regulation: Lac Operon |
88%
Level 1: 80%+
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| Assertion (A): | Lactose is termed as inducer. |
| Reason (R): | It regulates switching on and off of the operon. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True, but (R) is not the correct explanation of (A). |
| 3. | (A) is True, but (R) is False. |
| 4. | (A) is False, but (R) is True. |
Subtopic: Gene Regulation: Lac Operon |
88%
Level 1: 80%+
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