As you can see, genetic modification of crop plants is far from new.  Before the 20th century, people did not understand the underlying genetic and biochemical basis of heredity.  But they were still able to modify plants, as is obvious from the history of our major staple crops, corn, wheat and rice.  That is because change (a genetic change is called a mutation) is not only part of the chemistry of DNA, the hereditary material, but because the DNA is exposed to radiation from the sun and space, as well as to harmful chemicals, such as reactive oxygen species, produced in cells themselves the the course of their normal activities.  Among the plants normal activities are harvesting energy from the sun and converting it to sugars and breaking down high energy compounds to live. During the second half of the 20th century, geneticists, biochemists and molecular biologists learned a great deal about the structure of DNA, how information is coded in the DNA and how it is decoded in cells. In time, they figured out what a gene was and how to move it from one organism to another.  In the following slides, I will explain how novel genes are introduced into plants.