Nobel Prize for Chemistry 2020 | 08 Oct 2020

Why in News

Recently, Emmanuelle Charpentier of France and Jennifer A Doudna of the USA have been awarded the 2020 Nobel Prize in Chemistry for developing CRISPR/Cas9 genetic scissors, one of gene technology’s sharpest tools.

Key Points

  • The CRISPR/Cas9 genetic scissors can be used to change the deoxyribonucleic acid (DNA) of animals, plants and microorganisms with extremely high precision.
    • The CRISPR/Cas9 tool has already contributed to significant gains in crop resilience, altering their genetic code to better withstand drought and pests.
    • This technology has had a revolutionary impact on the life sciences and contributes to new cancer therapies. It has the potential of curing inherited diseases.
  • Discovery:
    • Charpentier, while studying the Streptococcus pyogenes, a harmful bacterium, discovered a previously unknown molecule, tracrRNA.
    • TracrRNA was part of bacteria’s ancient immune system, CRISPR/Cas, that disarmed viruses by cleaving (cutting) their DNA.
      • TracrRNA is programmed to locate the particular problematic sequence on the DNA strand, and a special protein called Cas9 (also known as genetic scissor) is used to break and remove the problematic sequence.
    • Both scientists collaborated and succeeded in recreating the bacteria’s genetic scissors in a test tube and simplifying the scissors’ molecular components making it easier to use.
    • In their natural form, the scissors recognise DNA from viruses but the duo reprogrammed them so that they could be controlled and can cut any DNA molecule at a predetermined site.

CRISPR Technology

  • The CRISPR (short for Clustered Regularly Interspaced Short Palindromic Repeats) technology for gene-editing was first developed in 2012.
  • It makes gene sequencing very easy, simple and extremely efficient providing nearly endless possibilities.
    • Editing, or modifying, gene sequences is not new and has been happening for several decades now, particularly in the field of agriculture, where several crops have been genetically modified to provide particular traits.
  • The technology replicates a natural defence mechanism in Streptococcus pyogenes that use a similar method to protect itself from virus attacks.
    • A DNA strand, when broken, has a natural tendency to repair itself but the auto-repair mechanism can lead to the re-growth of a problematic sequence.
    • Scientists intervene during this auto-repair process by supplying the desired sequence of genetic codes, which replaces the original sequence.
  • Concerns:
    • Ethical Concerns: Ease of altering DNA will allow more people to choose the characteristics of their progeny and this will hamper the natural process.
      • In November 2018, a Chinese researcher claimed to have altered the genes of a human embryo that eventually resulted in the birth of twin baby girls. It was the first documented case of a ‘designer babies’ being produced using gene-editing tools like CRISPR.
      • It was probably done without any regulatory permission or oversight which makes it even worse.
    • Not Fully Accurate: Few scientists have pointed out that CRISPR technology is not 100% accurate, and it is possible that some other genes could also get altered by mistake.
    • Lack of Rules and Guidelines: Doudna has been campaigning for the development of international rules and guidelines for the use of CRISPR technology and has also advocated a general pause on these kinds of applications till such time.

Source: DTE