Transgenic plants can be used as bioreactors to produce biomolecules like vaccines, antibodies, and enzymes. Genes encoding the desired products are inserted into plants, which then produce and store the proteins. This is an attractive alternative to microbial systems as it is lower cost and can perform post-translational modifications. A variety of plant tissues and organelles can be used, including seeds, chloroplasts, and hairy root cultures. The proteins must then be purified from the plant materials. Transgenic plants show promise for industrial and nutritional applications.