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Bt toxin protein crystals present bacterium Bacillus thuringiensis, do not kill the bacteria themselves because
- a)Bacteria are resistant to the toxin
- b)Toxins occur as inactive protoxins in bacteria
- c)Bacteria enclose toxins in a special sac
- d)None of these
Correct answer is option 'B'. Can you explain this answer?
Verified Answer
Bt toxin protein crystals present bacterium Bacillus thuringiensis, d...
Soil bacterium Bacillus thruingiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes). Bacillus thuringinesis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as an inactive toxin and is converted into an active form due to the alkaline pH of the alimentary canal that solubilities the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores which cause cell swelling and lysis and finally cause the death of the insect.
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Most Upvoted Answer
Bt toxin protein crystals present bacterium Bacillus thuringiensis, d...
The Correct Answer is Option B: Toxins occur as inactive protoxins in bacteria.
Explanation:
Bacillus thuringiensis (Bt) is a bacterium that produces a protein toxin called Bt toxin. This toxin is commonly used as a biological pesticide to control insect pests. However, the Bt toxin does not kill the bacteria themselves. The reason for this is that the Bt toxin occurs as inactive protoxins in the bacteria.
1. Nature of Bt Toxin:
The Bt toxin is produced in the form of protein crystals within the bacterium Bacillus thuringiensis. These crystals are made up of inactive protoxins, which means they are not toxic in their current form.
2. Activation of Bt Toxin:
In order for the Bt toxin to become active and toxic, it needs to be activated within the insect's gut. When an insect ingests the Bt toxin crystals, they are exposed to the highly alkaline pH in the insect's digestive system. This alkaline environment triggers the activation of the protoxins, converting them into active toxins.
3. Mode of Action:
Once activated, the Bt toxins bind to specific receptors in the insect's gut lining. This binding disrupts the integrity of the gut, leading to the formation of pores or channels in the gut epithelial cells. As a result, the insect's gut becomes leaky, allowing the contents of the gut to leak into the body cavity. This leads to a loss of nutrient absorption and causes the insect to die.
4. Protection of Bacteria:
While the Bt toxin is toxic to insects, it does not harm the bacteria themselves because the protoxins are produced and stored in a specialized compartment within the bacterial cell called an inclusion body. This inclusion body protects the bacteria from the toxic effects of the Bt toxin.
In conclusion, the reason why the Bt toxin does not kill the bacteria Bacillus thuringiensis is that the toxin occurs as inactive protoxins within the bacteria. These protoxins only become active and toxic when they are ingested by insects and exposed to the alkaline conditions of their gut.
Explanation:
Bacillus thuringiensis (Bt) is a bacterium that produces a protein toxin called Bt toxin. This toxin is commonly used as a biological pesticide to control insect pests. However, the Bt toxin does not kill the bacteria themselves. The reason for this is that the Bt toxin occurs as inactive protoxins in the bacteria.
1. Nature of Bt Toxin:
The Bt toxin is produced in the form of protein crystals within the bacterium Bacillus thuringiensis. These crystals are made up of inactive protoxins, which means they are not toxic in their current form.
2. Activation of Bt Toxin:
In order for the Bt toxin to become active and toxic, it needs to be activated within the insect's gut. When an insect ingests the Bt toxin crystals, they are exposed to the highly alkaline pH in the insect's digestive system. This alkaline environment triggers the activation of the protoxins, converting them into active toxins.
3. Mode of Action:
Once activated, the Bt toxins bind to specific receptors in the insect's gut lining. This binding disrupts the integrity of the gut, leading to the formation of pores or channels in the gut epithelial cells. As a result, the insect's gut becomes leaky, allowing the contents of the gut to leak into the body cavity. This leads to a loss of nutrient absorption and causes the insect to die.
4. Protection of Bacteria:
While the Bt toxin is toxic to insects, it does not harm the bacteria themselves because the protoxins are produced and stored in a specialized compartment within the bacterial cell called an inclusion body. This inclusion body protects the bacteria from the toxic effects of the Bt toxin.
In conclusion, the reason why the Bt toxin does not kill the bacteria Bacillus thuringiensis is that the toxin occurs as inactive protoxins within the bacteria. These protoxins only become active and toxic when they are ingested by insects and exposed to the alkaline conditions of their gut.
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Bt toxin protein crystals present bacterium Bacillus thuringiensis, do not kill the bacteria themselves becausea)Bacteria are resistant to the toxinb)Toxins occur as inactive protoxins in bacteriac)Bacteria enclose toxins in a special sacd)None of theseCorrect answer is option 'B'. Can you explain this answer?
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Bt toxin protein crystals present bacterium Bacillus thuringiensis, do not kill the bacteria themselves becausea)Bacteria are resistant to the toxinb)Toxins occur as inactive protoxins in bacteriac)Bacteria enclose toxins in a special sacd)None of theseCorrect answer is option 'B'. Can you explain this answer? for Class 8 2024 is part of Class 8 preparation. The Question and answers have been prepared according to the Class 8 exam syllabus. Information about Bt toxin protein crystals present bacterium Bacillus thuringiensis, do not kill the bacteria themselves becausea)Bacteria are resistant to the toxinb)Toxins occur as inactive protoxins in bacteriac)Bacteria enclose toxins in a special sacd)None of theseCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Class 8 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Bt toxin protein crystals present bacterium Bacillus thuringiensis, do not kill the bacteria themselves becausea)Bacteria are resistant to the toxinb)Toxins occur as inactive protoxins in bacteriac)Bacteria enclose toxins in a special sacd)None of theseCorrect answer is option 'B'. Can you explain this answer?.
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