CRISPR-CAS9

It is one of the process of genome editing.

HOW DOES IT WORK?

CRISPR is a RNA and CAS 9 is a nuclease.

Basically bacteria uses this system to prevent itself from viral DNA. In this system RNA formed by bacteria is responsible for the breakdown of the viral nucleotide (DNA).

CRISPR is a short RNA which is around 20 nucleotide long. As the bacteria generally knows which kind of viruses attack them, so they form the RNA in that manner.

NOW, As the RNA templates have complimentary strands for the DNA, the bacterial RNA binds with the viral DNA.This RNA is also known as the guide RNA or GRNA. CAS 9 that is the nuclease, recognizes the RNA DNA complex, come there and degrade the viral DNA selectively. 

WORKING OF THE CRISPR CAS-9

NOW, THERE MUST BE QUESTION POPPING IN YOU HEAD,

HOW DOES THE BACTERIAL RNA RECOGNIZES THE VIRAL DNA, AS BACTERIA ALSO HAVE ITS DNA?

SO, in viral DNA in the upstream from the recognizing region there is a PAM sequence present, which is not present in the bacterial DNA. 

IS THIS USEFUL TO HUMANS?

YES, we use this technique to selectively silence some region of our DNA with the help of a vector. There are many diseases being tested through this, they will work and give results. Diseases such as sickle cell anemia, cystic fibrosis, hemophilia etc. There are some more diseases in which this technique can give results such as cancer, HIV etc. as they are cell  and DNA related diseases. 

This technique can also be used to add a gene in the DNA. There are some diseases which occurs due to the lack of a particular gene. So this can incorporate a good gene and restore a genetic disorder.