Biotechnology in Medicine

by Georgina Cornwall, PhD

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    00:01 We can also use bacterial cells that have already introduced this to produce human genes.

    00:09 The human insulin gene is a great example of this. Now it is a little bit complicated because the human insulin gene as you can say in this flow here, we transcribe it and translate it and cut off the introns in such and then we form this polypeptide that is one single long chain, but it actually gets cleaved into places and there are disulfide bridges that hold it together, but it gets cleaved in two places essentially the point is that we have an alpha piece and a beta piece. Now to get the whole insulin piece bonded with these disulfide bridges, we actually introduce it into two different bacteria because there are going to be two pieces of DNA that are coding for it and so we can have one bacteria.

    01:01 We add that gene to the bacterial plasmid added to a bacteria, culture the bacteria and ideally he makes lots and lots and lots of the alpha subunit of this insulin molecule and then beta subunit can be made in the same way by a different bacteria and then eventually we bring those two molecules together in order to form human insulin. In this manner, we can have human insulin made in a petridish. We can amplify that sequence within all the bacteria and harvest it and give it to type I diabetes in order to treat their insulin deficiencies. A great use of biotechnology I think you might have to agree. Recombinant DNA technologies can also be used in the creation of vaccines.

    01:55 For example, let us take the herpes virus. The herpes virus, we can get the DNA from the herpes virus out of that virus and we can put it into an attenuated or harmless cowpox virus. We take the DNA from the herpes virus and we are going to put it into attenuated harmless virus by cleaving it with restriction enzymes and sticking it together with the harmless virus DNA, the attenuated virus and then we have a recombinant piece of DNA, pretty straight forward. We seemed to have covered the stuff already, but it goes into the virus and now the vaccine is made and the vaccine will then be injected into the human and this attenuated virus now is harmless to the human but contains DNA from herpes virus that the human body will now recognize. Its first exposure is in the vaccine. We will make some antibodies to that in our human immune response and then we can remember that the virus was there already and next time a little bit of it comes to us we can launch a full blown attack and kill that infection. Genetic engineering uses recombinant DNA technology and we can also use this technology in creating gene therapies. What is a gene therapy you might ask? Well, gene therapy involves taking a human stem cell from tissue, not embryonic stem cell necessarily, but from tissue that would become any sort of skin cell, for example, we can take cells from that. Let us say those cells on that person's arm that have been affected by skin cancer and we might want to repair them. So we take them some stem cell that could become skin cells and we can take good DNA and introduce it into a virus and we introduce that good DNA for the gene that is not broken and then we can have that virus infect these stem cells and deliver the good copy of the gene into those stem cells. We culture those stem cells and grow them and then give them back to the original person that they came from because they are genetically identical except for the fixed gene. Those cells will stay with that individual and ideally grow and repair the damaged area.

    04:35 This is the technology that we are using also to develop insulin being produced by our own pancreatic cells. So for someone who is a type I diabetic, this could be revolutionary treatment. We also are using it to develop treatments for things like cystic fibrosis and hemophilia as well as some forms of hereditary blindness. It is certainly an active field in cancer research as well as in solving issues with Parkinson's disease. In short, we are taking someone's original cells that belong to them changing the bad copy replacing it with the good copy and reintroducing that gene. Now earlier, we discussed the new system that has been discovered with Cas9 and the CRSPR sequence. With this technolgy, we now can cut much more specific areas of the DNA and have the potential to introduce the gene of interest into a very specific location. Previously we had restriction enzymes that cut in maybe sort of random places and you had to hope that the gene would be downstream of an area that is actually going to be transcribed and translated. With the CRSP/Cas9 system, we can now say,"Hey, we know this is where it starts being transcribed and translated. Let us put it in right here." You can order the sequence, cut the DNA insert the genes. We are at the forefront of some really amazing progress in gene therapies.

    About the Lecture

    The lecture Biotechnology in Medicine by Georgina Cornwall, PhD is from the course Biotechnology.

    Included Quiz Questions

    1. …the replacement of defective gene with the fully functional gene in an individual’s cells to treat a hereditary disease.
    2. …the replacement of defective mRNA with the functional one in an individual’s cells to treat a hereditary disease.
    3. …the replacement of defective rRNA with the functional one in an individual’s cells to treat a hereditary disease.
    4. …the replacement of defective ribosome with the functional one in an individual’s cells to treat a hereditary disease.
    5. …the replacement of defective tRNA with the functional one in an individual’s cells to treat a hereditary disease.
    1. Human immunodeficiency virus
    2. Adenovirus
    3. Herpes simplex virus
    4. Vaccinia
    5. Adeno-associated virus
    1. rDNA vaccines
    2. Growth hormones
    3. Human insulin
    4. T-cells
    5. Liver cells

    Author of lecture Biotechnology in Medicine

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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