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Genetic engineering is a process which involves the alteration of the genes of an organism. Recombinant DNA is a tool used in genetic engineering; a short segment of DNA from one organism is "recombined" with the DNA of another organism.
One of the first attempts to create recombinant DNA was to help people with diabetes. At the time, the only way to prevent someone with diabetes from starving to death (remember, type I diabetics can't produce insulin and therefore can't move sugar from their blood to their hungry cells) was to give them cow's insulin. Cow's insulin was expensive, difficult to come by and didn't work well; people with diabetes had very foreshortening, poor-quality lives.
Scientists used genetic engineering to rapidly produce human insulin, which is far more effective than cow's insulin. They used restriction enzymes to introduce cuts into DNA extracted from cells swabbed from the inside of your cheek, for example. These cuts reduced the human genome to smaller-sized pieces that are easier to manage. They then took these pieces and inserted them into small circles of DNA called plasmid DNA. In the diagram below the dark strand is the human DNA, while the yellow is the plasmid. These plasmids are relatively easy to insert into transformation (briefly opening holes in a cell's plasma membrane so DNA outside the cell can be taken in and expressed). The plasmids also contain instructions for how to get rid of cells that didn't take up the correct DNA, as well as instructions for producing the protein encoded in the recombinant DNA.
This technology was used to introduce the gene for human insulin into E. coli, which grows rapidly and can produce this effective treatment for diabetes very cheaply. Thanks to this transgenic organism (an organism that contains genes from another organism), people with diabetes can live long, healthy lives.
Since the use of genetic engineering to create a therapy for diabetics, the technology has continued to improve, and the number of applications has increased.
For example, instead of isolating a whole bunch of DNA, cutting it up with restriction enzymes and hoping the correct gene gets inserted into one of your billions of plasmids, we can use polymerase chain reaction (PCR) to copy the precise gene in a couple of hours.
Besides creating medicinal proteins and molecules, genetically modified organisms (GMOs) can be used to make our environment cleaner and safer. For example, bacteria can be genetically modified to have genes that allow them to eat oil. These GMOs have been deployed at oil spills. This genetic engineering application is called bioremediation.
Genetic engineering has also been used to make food more affordable and more nutritious. Plants are being used in genetic engineering, and they can produce genetically modified foods. These genetically modified foods can be pest resistant and more resilient. They also can be genetically modified to do things like provide more vitamins.
In a way, this technology isn't new; people have been selectively breeding animals and hybridizing plants for thousands of years. Everything we eat has been "genetically modified" over generations. The benefit of genetic engineering technology is that it is more precise, so it introduces less risk of including harmful DNA along with the beneficial DNA. It's also faster and cheaper; reverting back to old insulin technology, for example, would be a death sentence to a lot of diabetics.
Gene therapy is a process that's used to help fix genetic diseases. As of right now, its use is not widely spread because it's still very experimental and costly. There are several ways gene therapy can be used. It is hoped that gene therapy can be used to replace or edit mutated genes.
EXAMPLE
You may have heard about the pregnant mother who has HIV. There was a very good chance her unborn children were going to contract the virus. CRISPR technology was used to alter the CCR5 receptors in the babies' T cells. This is a mutation that already exists in many people; people who are homozygous for this mutation are immune to HIV. Genetic engineering was used to give these babies a mutation that already exists and make them immune to their mother's HIV.There are a couple of different ways in which genes can be inserted into a person in the process of gene therapy:
Cystic fibrosis is another example of a disease that has had some trials with gene therapy. With this disorder, scientists have used a virus to deliver normal copies of a gene to the respiratory system. With cystic fibrosis, you get a buildup of mucus in the respiratory system. By using this virus, they can deliver normal copies of the gene to the respiratory system to help with this condition.
The most common use of gene therapy thus far has been with cancer. It's had the biggest success thus far with gene therapy of any of the other diseases that they've done trials with.
Cloning is the process of producing a genetic copy of a cell or an organism. So far, scientists have cloned bacteria in recombinant DNA technology and embryos for stem cell use. They've also cloned animals, one of the most famous examples being Dolly the sheep.
There are two different types of cloning that can be used:
Additionally, there has been an ethical debate about altering the genetic makeup of an embryo before it's implanted. Many people consider this to be unnatural because rather than letting nature take its course, this process involves messing with aspects of biology that are typically out of people's hands. However, cloning can certainly be a useful tool.
Source: This work is adapted from Sophia Author Amanda Soderlind