What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?

(N/A) Cry proteins are toxic proteins encoded by $cry$ genes. These are produced by the bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
In the bacterium,these proteins exist in an inactive protoxin form.
When an insect ingests these proteins,the alkaline $pH$ of the insect's gut solubilizes the crystals and activates the toxin.
The activated toxin binds to the surface of midgut epithelial cells and creates pores,causing cell swelling and lysis,which leads to the death of the insect.
Humans have exploited this mechanism to develop insect-resistant transgenic crops,such as $Bt$ cotton and $Bt$ corn,by incorporating $cry$ genes into the plant genome.