CRISPR — Gene editing
Introduction:
Have you ever written an algorithm but didn’t get the outputs you desired, so you go back and change the way you want the result to be? Or have you ever taken a long drive but suddenly your tyres get punctured, so you stop at the side of the road and change it, and then continue your drive? But have you ever heard that you can literally edit a part of the DNA (as you want) and interchange them with healthy DNA to cure a disease? That is the miracle of Science.
“Every Science begins at philosophy and ends at art; it arises in hypothesis and ends in achievement” is a very famous quote written by an American author. That is how CRISPR started. It stands for Clustered regularly interspaced short palindromic repeats. The CRISPR technology allows scientists to make changes in the DNA in cells that allow to cure genetic diseases. The CRISPR technology first came about through a basic research project that was aimed at how bacteria fight viral infections. There are a lot of viruses present in the bacterial environment and it has only a few minutes before the bacteria gets infected with it and dies. So, to protect itself from the virus, they have in their cells an immune system called CRISPR, that allows them to detect the viral DNA and destroy it. Part of the CRISPR system is a protein called Cas 9, which is able to seek out, cut and eventually degrade the DNA in a specific and precise way. CRISPR was found by a microbiologist in the late 1980’s but the thought to use these for gene editing by sniping out a part of the DNA and replacing it with another pair was invented by Scientists and Nobel laurates, Jennifer Doudna and Emmanuelle Charpentier.
Methodology:
When a virus infects a cell, they inject their DNA, and in the bacteria the CRISPR system allows the DNA to be plucked out of the virus and insert little bits of it into the chromosome. These bits of viral DNA then get inserted at a site called CRISPR and this mechanism allows it to be recorded for future generations. So, the next time a virus infects the bacteria, the progeny of the bacteria will recognize the viral sequences and will be immune. Once the bits of DNA have been inserted into the bacterial chromosome, it copies it in the form of an RNA, and they bind to the protein Cas9. All these forms a small complex and searches through all the DNA in the cell, to find sites that match the sequences in the bound RNAs. After those sites are found, the complex binds to that site and cuts the viral DNA. The main principle to this technique is that it is programmable, so it can be programmed to recognize particular DNA sequences and make a break in the DNA at that site.
These cells have the ability to detect broken DNA and repair it. If there is a break in the double helical structure, it can be fixed by integrating a new piece of DNA or if it’s a mutation, the preferred DNA is converted to RNA and made to bind with the Cas9 protein in CRISPR and it immediately finds the mutation and cuts it and replaces with the right sequences. This is being used to treat diseases like Sickle cell Anaemia, Cancer, blindness, AIDS, Muscular dystrophy etc.
Challenges and future scope:
Apart from correcting the disease-causing genetic disorders, the CRISPR technology can also be used for elimination of disease-causing microbes, resurrection of species, eradication of harmful pests and creation of better, healthier varieties of food.
However, many scientists are also conducting researches on age reversal and genetically engineered baby where they artificially induce genes into the embryo — according to the parents’ wishes. Nature is there for a reason and there is a thin line between Science and Ethics. We should not let greediness get in the way of morality.
Reference -
- How CRISPR lets us edit our DNA | Jennifer Doudna — TED — YouTube (https://www.youtube.com/watch?v=TdBAHexVYzc)
- Labiotech — 7 Diseases CRISPR Technology could cure (https://www.labiotech.eu/crispr/crispr-technology-cure-disease/)
- Netflix documentary — human nature.
