|MadSci Network: Genetics|
People have been using selective breeding for centuries. That is how we have different breeds or dogs, cats, horses, cows, and all the different types of plants. Corn is actually a selectively bred crop. The wild type of corn is actually from South America. It is call Mais and the seeds come forn the top of the plant and the pollen from the sides. Domesitc corn has these traits reversed. In a selective breeding program you choose traits that you are interested in improving. For example temperment or colour in a dog breed. You choose parents that have the desired traits and breed them together. Esentially the human controls who mates with who insted of letting nature take its course. It usually take generations upon generations to see a change occuring by selective breeding. It took several hundreds of years to produce the corn that we know today. Genetic Engineering make the cahnges a lot faster. Say you are selectively breeding for a potato that is naturally resistant to potato blight (a disease that devistated the potato crop in Ireland and caused many people to starve). If you were to do this by slective breeding you would take all the plants that were resistant to the disease and breed them together (F0). You would then try and find the offspring(F1 generation) that were resistant as well. These would be bred with either the parents (back cross) or other F1 to produce an F2 generation. Eventually you would end up with plants that only produced resitant offspring. Biotechnology (i.e. Genetic engineering) helps to speed up this long drwn out process. One of the ways to do this is to develop molecular markers. These markers are genes that are often seen associated with the desired traits. Looking at a plant you can't see if it is resistant to a disease. These markers help the breeding programs identify the desired plants sooner so there is less time wasted. The second thing that biotechnology does (and this is more genetic engineering) is to actually copy the gene that makes the plant resistant and insert it into the plants genome. A good site that explains this process is http://www.geneti cengineering.org/dna6/default.htm It also compares to regular mating programs. Good Luck.
Try the links in the MadSci Library for more information on Genetics.