The Concepts Of Crispr & Dna
CRISPR is a revolutionary gene-editing tool that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence. CRISPRs are regions in the bacterial genome that help defend against invading viruses. These regions are composed of short DNA repeats and spacers. The CRISPR technique helps our bodies from recurring viral attacks. It gets DNA from an invading virus processed into short segments which are then inserted into the CRISPR sequence as new spacers.
CRISPR “spacer” sequences in the DNA are transcribed into short RNA sequences which then guides the system to matching sequences of DNA. When the target DNA is found, Cas9 – one of the enzymes produced by the CRISPR system – binds to the DNA and cuts it, shutting the targeted gene off. This technique is used by scientists to target and either fix or exploit a number of genetic mutations in humans, animals, insects and plants.One way CRISPR is used in research is for the treatment of cancer such as HIV. Researchers have shown the CRISPR/Cas9 system editing the HIV-1 genome and blocking its expression replication, and immunizing uninfected cells against HIV-1 infection.
Another way CRISPR has been used in research is by finding a way to correct a mutation in a gene that is causing a disease e.g. β-thalassemia (mutations in the human haemoglobin beta (HBB) gene cause poorly functioning protein). Researchers created stem cells from patients and used CRISPR/Cas9 to fix the mutated gene. These cells grew and contained the normal haemoglobin beta (HBB) gene.
An advantage of CRISPR is that it is faster, cheaper and more accurate than previous techniques of editing DNA and has a wide range of potential applications. Another advantage is that mutations can be introduced in multiple genes at the same time by injecting them with multiple gRNAs.
A disadvantage of CRISPR is there has been a lot of interest in and debate about the potential to edit germline cells. Because any changes made in germline cells will be passed on from generation to generation it has important ethical implications. Another disadvantage is that in certain cases, the Cas9 nuclease will create unwanted cuts in the DNA, or will only cut the DNA in some cells. Just a few years after its invention, CRISPR gene editing is already having a major impact on biomedical research. It makes it easy to introduce specific mutations, to find out why they make cells cancerous or predispose people to diseases.
