Bt Crop Mechanism — a labelled NEET Biology diagram with a definitions lexicon.
Bt crop mechanism Labelled parts: Bacillus thuringiensis, Cry gene, Plant DNA, Plant cell, Transgenic plant, Cry protoxin, Midgut epithelial cells, Protoxin, Alkaline gut, Active Bt toxin, Bt toxin, Insect larva, Bt plant tissue. B. thuringiensis is a naturally occurring bacterium that produces crystalline proteins (Cry proteins) toxic to specific insect larvae. It is used as a biological pesticide. FYI: The toxicity of B. thuringiensis is highly specific, meaning it targets certain insect orders (e.g., Lepidoptera) and is generally safe for mammals. Cry genes encode the genes responsible for producing crystalline proteins (Cry proteins) in Bacillus thuringiensis . These proteins are insecticidal toxins. FYI: The Cry genes are often inserted into plant genomes to confer resistance against specific insect pests (e.g., Bt crops). The protoxin is the inactive, crystalline form of the Cry protein produced by B. thuringiensis . It must be activated in the insect gut to become toxic. FYI: In the alkaline gut of the insect, the protoxin is solubilized and activated by proteases, forming the toxic pore-forming toxin. These are the specialized cells lining the midgut of insects, which are responsible for the digestion and absorption of nutrients. They contain receptors and enzymes necessary for digestion. FYI: In the context of insect immunity, these cells are key sites for the recognition and encapsulation of pathogens. A protoxin is an inactive precursor molecule of a toxin that requires further processing (e.g., cleavage or conformational change) to become biologically active. It is a common mechanism for regulating toxin activity. FYI: The conversion of a protoxin to its active form often occurs in a specific physiological environment, such as the alkaline gut. The alkaline gut refers to the specific physiological environment within the insect digestive tract where the pH is high (alkaline). This environment is crucial for the activation of certain toxins, like Cry proteins. FYI: The high pH of the alkaline gut facilitates the solubilization and enzymatic activation of the crystalline protoxin.