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Genetically Modified
Organisms (GMOs)
Any microorganism, plant or animal that
has purposely had its genome altered
using genetic engineering technology
Traditional Genetic Modification
• Also called Selective Breeding
• Farmers would always save the best seeds
(bigger, sweeter or more resistant to
disease, etc) from their crops to plant for
next year.
• As a result each year the farmer got slightly
better crops. Change was slight but over
many generations the change was
significant.
Selective Breeding
You needed to select for the biggest ears of
corn & plant those seeds so that over time
(several seasons) your entire crop would
consist of large ears of corn.
For example…..
• Balsas teosinte, a
wild grass typically
found in Mexico,
was modified into,
drum roll
please……
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Modern Corn!
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Transgenic Manipulation
• One or more genes are artificially
inserted into the DNA of the plant’s
chromosomes.
• The gene can come from the same type
of plant or even another type of
organism
Bt Crops
• Plants with the Bt sequence of genes
can produce proteins that protect them
from various insects such as European
corn borer, southwester corn borer,
tobacco budworm and Colorado potato
beetle.
Let’s Engineer…..
• Take toxin from BT DNA and combine with a
vector (What is a vector?)
 Short piece of DNA capable of replicating on its
own when inside a bacterial cell.
• Now another gene which will make the plants
resistant to a herbicide is added.
• The vector, which incorporates the Bt gene, is
now placed into a bacterium cell.
How do we engineer a vector?
• First, we need our DNA of interest. We cut
it out of host cell DNA using restriction
enzymes
• Restriction enzymes cut DNA at specific
DNA sequences and Leave “sticky” ends
• Use restriction enzymes to cut our vector
• Add DNA of interest to the vector
Restriction Enzyme
Let’s Engineer…..
• The goal is to create a plant that can
produce a protein that will kill insects
that try to eat it.
• The bacteria Bacillus thuringiensis
contain a gene that carries the
instructions for making this protein.
• You created a genetically modified
plant that contained the Bt gene so that
the plant will also be able to produce
this protein.
Making a GMO
• Step 1-remove the gene (Bt) you are interested in
inserting into another organisms DNA
• Step 2-insert that “gene of interest”(Bt) into a
vector (carrier), which is a small piece of DNA
that is capable of replicating on its own when it is
inside a bacterial cell
Now the vector
contains your
gene!
You will also
insert a gene
for resistance
to herbicide.
Making a GMO
• Step 3-allow the bacteria (Agrobacterium)
the opportunity to take up the vector
(plasmid)
• Step 4-place bacteria on an agar petri dish
so that they can reproduce, every new
bacterial cell made will have a copy of
the vector containing the Bt gene
Agrobacterium
• Causes disease in plants.
• Has the ability to transfer a portion of
it DNA into plant cells
• Once inside a plant cell, its DNA will
be incorporated into the DNA of one of
the plant’s chromosomes.
Transformation is…
• Taking in and then expressing DNA
from outside the cell.
Making a GMO
• Step 5-add plant leaf cells to
same petri dish where modified
bacteria is growing, DNA of
bacteria will enter leaf cells and
nucleus of the cell
• The Agrobacterium DNA, which
includes the Bt and herbicideresistance genes, is now part of
the plant cell’s DNA
Making a GMO
• Step 6: add the plant leaf cells to a petri dish with
growth medium and they will begin to reproduce to
form roots, stems, & leaves
• Step 7: spray plants with herbicide, only the plant
cells with the herbicide resistance gene will survive
Making a GMO
• Step 8-transfer the plant
cells to soil
• You will now have a plant
in which all of the cells
have the Bt gene
• Any insects that try to eat
these plants will be killed
Why do we transform
bacteria
• We can add DNA we want to
bacteria, to make them produce
things we want like
• Penicillin (and other antibiotics)
• Insulin (for diabetics)
• HGH (human growth hormone)
How do we transform
bacteria
• Cells rarely pick up free floating DNA
• DNA must be stored inside a vector for
cells to absorb it
• Vectors are molecules that can carry
DNA
• Bacteria have plasmids that store DNA
• Plasmids can be used as a vector
• Viruses can be used as a vector
What is a plasmid?
Plasmids are
chromosome
like structures in
bacteria, which are
made of
proteins and carry
DNA.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Genetic engineering
• Artificially adding DNA to an organism
• Recombinant DNA is DNA from two
organisms that has been spliced together in
genetic engineering
• Flavr Savr Tomato
• GM Salmon
• Genetically-Engineered Food Might Fight
Disease