Therefore, a slight rearrangement of the bases in a DNA molecule may alter the organism's traits or characteristics. Throughout evolution, natural selection has caused organisms to adapt to their surroundings. This is a very slow process. Through reproduction, the parents transmit genes to the offspring. Understanding this enabled us to use classical breeding thecniques to improve corps and domestic animals.
Classical breeding involves humans introducing new genetic material to the offspring.
However, organisms are capable of reproducing only within species or between very closely related species. Therefore, calssical breeding was limited to generating hybrids within a given species or between closely related ones. Genetically engineered crops have foreigh genes. The gene introduced into the plant may have originally belonged to a totally different plant, a microbe, or even an insect or an animal. For example, Bt corn, a genetically modified crop, contains genes belonging to a bacterium called Baccilus thurengiensis .