MadSci Network: Genetics

Re: what is the difference between selective breeding and genetic engineering?

Date: Wed Feb 14 16:25:08 2001
Posted By: Wendy Shearer, Staff, Plant Molecular BIology, Lorus Therapeutics
Area of science: Genetics
ID: 982104513.Ge

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 It also 
compares to regular mating programs. 

Good Luck.

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