Fifty years ago, scientists discovered that DNA carries a code that provides us with every trait we have. Since it's discovery scientists have not only discovered what each part of our DNA codes for, but also ways to manipulate it in ways to produce plants, animals, bacteria, and other organisms with altered genetic make-up. Such organisms can be used for a variety of reasons, including the production of pharmaceutical materials much more efficiently than previous techniques.
Recombinant DNA
In a series of experiments in the late 1960s and early 1970s, Stanley Cohen, Herbert Boyer, and their colleagues developed the techniques necessary to recombine genes in bacterial plasmids. Bacteria have a large circular chromosome which codes for their main functions, as well as small circular plasmids which can code for additional information and replicate independently. Plasmids can leave the E. coli bacteria and enter other E. coli bacteria cells without affecting the life of the cell itself. They took the gene responsible for ribosome production in African frogs and added it to the plasmids of E. coli bacteria. These plasmids are recombinant DNA because they combined with the frog DNA when reforming then reenter the bacteria trough a process called transformation. We call this plasmid a vector because it now contains the gene of interest from the frog DNA and can bring it into the E. coli bacteria. Each bacterial cell produced from the transformed E. coli bacteria could now also produce frog ribosomes as shown below.
In a series of experiments in the late 1960s and early 1970s, Stanley Cohen, Herbert Boyer, and their colleagues developed the techniques necessary to recombine genes in bacterial plasmids. Bacteria have a large circular chromosome which codes for their main functions, as well as small circular plasmids which can code for additional information and replicate independently. Plasmids can leave the E. coli bacteria and enter other E. coli bacteria cells without affecting the life of the cell itself. They took the gene responsible for ribosome production in African frogs and added it to the plasmids of E. coli bacteria. These plasmids are recombinant DNA because they combined with the frog DNA when reforming then reenter the bacteria trough a process called transformation. We call this plasmid a vector because it now contains the gene of interest from the frog DNA and can bring it into the E. coli bacteria. Each bacterial cell produced from the transformed E. coli bacteria could now also produce frog ribosomes as shown below.
Gel Electrophoresis <--- click for virtual lab
In order to create a DNA Fingerprint, DNA is first amplified using a polymerase chain reaction (PCR). Basically this means a small amount of DNA can be copied over and over again so that it can eventually be made visible. Next, the DNA is cut using restriction enzymes, leaving behind different sized fragments of DNA. A Gel Electrophoresis uses an electric field to pull the negatively charged DNA strands through a gel. The smaller strands travel faster, so they travel the farthest while the larger strands travel the shortest distance. Because everyone's DNA is different, everyone's DNA fingerprint is also different. The same restriction enzyme might cut one person's DNA 1,000 times and someone else's 800 times.
In order to create a DNA Fingerprint, DNA is first amplified using a polymerase chain reaction (PCR). Basically this means a small amount of DNA can be copied over and over again so that it can eventually be made visible. Next, the DNA is cut using restriction enzymes, leaving behind different sized fragments of DNA. A Gel Electrophoresis uses an electric field to pull the negatively charged DNA strands through a gel. The smaller strands travel faster, so they travel the farthest while the larger strands travel the shortest distance. Because everyone's DNA is different, everyone's DNA fingerprint is also different. The same restriction enzyme might cut one person's DNA 1,000 times and someone else's 800 times.
Transgenic Organisms
Not only can bacteria be genetically engineered to produce human proteins, plants and animals can also have genes added to their genome from other organisms to change their functions. Try the Transgenic Fly Virtual Lab and see just how this process works. Notice that the only changes made to the fruit flies are the red eyes and the glowing since those are the only genes we added to their genome.
Not only can bacteria be genetically engineered to produce human proteins, plants and animals can also have genes added to their genome from other organisms to change their functions. Try the Transgenic Fly Virtual Lab and see just how this process works. Notice that the only changes made to the fruit flies are the red eyes and the glowing since those are the only genes we added to their genome.
The GMO "Debate"
Pros
Organisms can grow in stressful environments Organisms can be grown with more nutrition Organisms can be produced in large numbers Organisms can be produced more quickly Plants can be grow resistant to insects rather than sprayed with pesticides. Plants can be grown to have a longer shelf life Plants can be grown resistant to weed killers Pharmaceutical proteins can be produced cheaply using bacteria Pharmaceutical proteins can be produced cheaply using animals Time and money will be saved No evidence of negative effects on human health have been indicated |
Cons
People find it morally wrong to cross different organism's DNA People find it wrong to change naturally occurring organisms The technological advantage of GMOs can only be afforded by large companies Large companies control the food market Genetically modified plants can cross pollinate with natural plants The placement of the new gene could possibly affect the rest of the genome Growing plants to resist insects may be harmful to pollinators like bees and butterflies Organisms can be created to be used as weapons |
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