how/why do we modify crops?

how can we test whether or not a crop has been
​ genetically engineered? 

Btw...the Bt toxin is used topically to prevent insect damage.

It has been EPA approved since 1961 and is formulated in over 130 products.

To reproduce, Bt makes spores that grow into new bacteria which synthesize proteins that are toxic to insect larvae when eaten. Because Bt comes from a natural source, it is called a biopesticide.​ In general, biopesticides tend to pose fewer risks than typical human-made pesticides.

There are many types of Bt. Each type or strain affects different insect groups. Target insects include the beetle family, the fly family including mosquitoes, and the butterfly family. It is used to kill beetles and the larvae of mosquitoes, black flies, and moths. Bt is also toxic to nematodes.

https://biosecurity.fas.org/education/dualuse-agriculture/2.-agricultural-biotechnology/bt-corn.html

Genetically Modified Organisms

                         So, what are we doing today and next week...?
    this week:
​1. Extract corn DNA from food products.
2. Test the presence of the Bt gene by first amplifing the DNA via PCR on the extracted DNA.
     you will use primers specifically designed to target a sequence within the Bt gene.
    *If the Bt gene is present, amplification will be successful.
    *If the Bt gene is not present, amplification will not be successful.

      please refer to the PCR subpage
      for a refresher... 
     
​    

​   and then next week:
3. Perform a gel electrophoresis to visualize the presence or absence of amplified sequences. Amplified
    sequences will appear as a specific band on the gel. The presence or absence of this band and
    comparisons to control samples will confirm whether the food product contains the Bt gene produced
    via genetic engineering.
    Next week, we'll be referring to the link below for instructions on how to perform a gel                                      electrophoresis...






    We'll also hold our GMO debate during the time the gel is running ( approx. 1 hour).
    Debate prep assignments were distributed during the lab on 11/8.
    Students absent on the 8th will instead need to complete the 11/15 assignment posted on Canvas.     

a genetically modified organism (GMO)
​is a plant, animal or microbe whose DNA has been altered via genetic engineering with an intended goal to produce a helpful  trait such as drought tolerance, disease resistance, or increased nutrient value. 

The  the gene for the Bt toxin is inserted it into the cells of corn (or cotton plants) at the embryo stage. The resulting mature plant has the Bt gene in all its cells and expresses the insecticidal protein in its leaves.

Bt modified crops produce a protein called delta-endotoxin which is lethal to European corn borers
which love to feast on corn plants. 
 Farmers who plant Bt crops do not have to apply pesticide because the plants produce the toxic protein inside their cells.
​When the corn borers feed on the genetically modified plant, they die. 

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and btw...
here's why the protein is toxic to certain insects...

genetic engineering inserts genes for selected traits
​directly into crop plants.
These genes do not have to originate from the same plant species – in fact, they do not have to come from plants at all. One popular class of GM crops has a gene from the soil bacterium
Bacillus thuringiensis (Bt)
inserted into their genomes.

Golden rice 

​is produced via genetic engineering. Essentially, the rice is programed to biosynthesize beta-carotene, a precursor of vitamin A.
Severe vitamin A deficiency results in
blindness, am increases risk of death fron from measles and severe diarrhea in children. Vitamin A deficiency is
greatest in Africa and South Asia.