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……

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Modern Corn!

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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.

• 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 herbicide-resistance 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

Making a GMO

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.

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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