For thousands of years genetics has made an impact on agriculture. When farmers, ranchers, and herders employ selective breeding to increase their yield, they are using a kind of genetic engineering. They control the reproduction of their plants and animals so that each new generation has as many beneficial genes as possible. With such a history, then, it is no wonder that now, at the dawn of the twenty-first century, agriculture is one of the industries leading the way in cutting-edge gene manipulation techniques.

Transgenic Animals
Transgenic animals are animals that have had foreign genes implanted into their DNA structure. These genes often help the animal fight diseases, grow stronger, or withstand harsh environments. An antifreeze producing gene, for example, taken from cold water flounder has been inserted into certain kinds of salmon so that they can be raised in colder climates.

To make an animal transgenic, foreign genes must be inserted into a freshly fertilized egg before it begins to develop. The first step is to identify the desired gene in the donor cells. Once the target is found, restriction enzymes are used to cut the gene out of its DNA chain. Next, the gene is clipped into the DNA molecule of a bacterium, which will act as the carrier of the trait to the animal. The bacteria carriers are then allowed to grow into a colony, and are radioactively tagged to ensure that they have the desired gene. Once the carrier is ready, it is used to transplant the gene into a host embryo. This embryo is then either duplicated or immediately inserted into a surrogate mother so that it may develop.

Plants
The process involved in genetically engineering a plant is similar to that for an animal. The target gene must be found, cut, and transplanted into a carrier organism which will implant it in the host. The benefits of manipulating plants in this manner are varied. Soybeans have been altered to increase their amino acid content (making them a healthier food source). Photosynthesis can be made more efficient in some green plants. Fruits can be given a strong resistance to bruising. A crop's defenses against disease and pests can be increased.