CRISPR

 

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It is a very crucial technology. It is likely to have unprecedented impact on mankind. UPSC in last few years have asked a number of Questions on Land-mark developments and Since it is a revolutionary development, it is important for mains 2017.

What is CRISPR?

  1. It is a revolutionary gene editing technique that scientists have borrowed from nature.
  2. CRISPRs (clustered regularly interspaced short palindromic repeats) are sections of DNA, while CAS-9 (CRISPR-associated protein 9) is an enzyme.
  3. Bacteria use them to disable attacks from viruses.

Working of the CRISPR

  1. Crispr scans the genome looking for the right location and then uses the Cas9 protein as molecular scissors to snip through the DNA.
  2. Cas9 endonuclease – guide RNAs direct it to a particular sequence to be edited.
  3. When Cas9 cuts the target sequence, the cell repairs the damage by replacing the original sequence with an altered version.
  4. Unlike other gene-editing methods, it is cheap, quick, easy, safer and more accurate to use because it relies on RNA–DNA base pairing, rather than the engineering of proteins that bind particular DNA sequences.

What is Genome Editing?

  1. It is a type of genetic engineering in which DNA is inserted, deleted or replaced in the genome of an organism using engineered nucleases, or “molecular scissors”.
  2. These nucleases or enzymes create site-specific double-strand breaks (DSBs) at desired locations.
  3. The induced double-strand breaks are repaired through end joining or recombination, resulting in targeted mutation.

CRISPR/Cas9 Applications

Arguably, the most important advantages of CRISPR/Cas9 over other genome editing technologies is its simplicity and efficiency.

Basic Science

To date, the CRISPR/Cas9 gene editing tool appears to work in nearly every organism, from micro-organisms to monkeys, and in every cell type: kidney, heart and those, like T-cells, that researchers had previously found difficult to modify.

Agriculture

Some of the earliest papers using CRISPR/Cas9 for gene editing focused on crops important for agriculture such as rice and wheat. It was realized early on that this system could be utilized to specifically alter the DNA of these crop species to improve traits like disease and drought tolerance.

Disease Modeling

Disease modeling using animals has been a hurdle for study of many types of human diseases due to the difficulty in generating genetically modified animals that accurately recapitulate human pathology. The process was inefficient and inaccurate or simply impossible to do. CRISPR-Cas9 has allowed for generation of transgenic animals like rats, monkeys and other animals which are more suitable for human disease modeling than mice and thus permit better drug-development tests.

Gene Therapy

In 2014, CRISPR-Cas9 was used in mice to correct a mutation associated with a human metabolic disease called tyrosinaemia (Yin et al., 2014). It was the first use of CRISPR/Cas9 to fix a disease-causing mutation in an adult animal and an important step towards using the technology for gene therapy in humans.

Concerns related to CRISPR Tech.

  1. CRISPR is basically knock out strategy to silence the gene by inhibiting the RNA polymerase activity inside the nucleus. It’s still in the nascent stage, so it would be hard to comment about the major disadvantages
  2. But it’s very labour intensive and high cost oriented technique than RNA interference which provides a complete gene knock down within the cytosol with higher efficiency.

The Way Forward

  1. CRISPR/Cas9 gene editing technology is being touted as one of the biggest biotechnology breakthroughs of the century
  2. This new technology is a powerful tool for manipulating the genomes of not only mice but also somatic and embryonic stem cells from other species, including humans.
  3. It is likely that the refinements of these systems will continue and that they will be adapted in new ways to create ever more sophisticated animal models for and genetic therapies for treating human diseases.

Question

Q.) “CRISPR technology is much faster, yield better results, and is relatively easy to do.” Examine.

Source

http://cellculturedish.com/2016/05/crispr-cas9-system-applications/

https://www.taconic.com/taconic-insights/gems-design/crispr-genome-engineering-advantages-limitations.html

https://www.jax.org/news-and-insights/jax-blog/2014/march/pros-and-cons-of-znfs-talens-and-crispr-cas

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