Okay, so lets rewind a bit. Roundup is a brand name used by Monsanto for a type of herbicide called "glyphosphate" While it was under patent protection for 20 years, those patents all expired back in 2000 so now many companies market similar herbicides. These products are used by farmers to kill off smaller plants like grasses and bacteria that spread in the wild and would use nutrients in the soil that the farmer would rather be absorbed by their crops. It does this by blocking the creation of a few key proteins needed by all cells. This doesn't affect insects for the most part as animals don't make these proteins ourselves, we have to eat them ("essential amino acids"). But in plants, it kills them by denying them these required proteins.
Enter "Roundup Ready Soybeans" (and others, soybeans were the first though). They took genes from a few sources (a specific bacterium, a virus that infects cauliflowers, and a petunia flower) and combined to create a new method to synthesize those essential proteins, spec