Prelims cum Mains Science & Tech

Gene Editing | CRISPR/Cas9 : Promises & Challenges

What is CRISPR?

  • CRISPR stands for “clustered regularly interspaced short palindromic repeats”.
  • It is a method of DNA editing more efficient than ones available.
  • CRISPR uses an enzyme called Cas9 to cut strands of DNA at precisely targeted locations.
  • This allows one to insert new genetic material into the gap. 
  • CRISPR promises to revolutionize gene editing in organisms, by modifying inherited genes to spread a trait throughout a population.
  • CrispR is a replica of the natural process when a virus infects a bacterium.
  • When a virus gets in to bacterial cell wall, it becomes integrated into the bacteria’s genome.
  • From there, the viral DNA will replicate and become translated/transcribed into proteins which will eventually form a newly synthesized virus.
  • In order to defend against viral infection, bacterium evolved the CRISPR/Cas9 system adaptive immune system.
  • Within this system, ‘bacterial’ CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) spacer sequences are transcribed into RNA which guides a Cas9 endonuclease to matching regions of ‘viral’ DNA within the hosts’ genome.
  • The Cas9 endonuclease then unwinds the host cell DNA and cleaves/removes the infectious viral DNA from the bacterium.


How do Genes work?

  • Every cell in an organism contains all of the information needed to manufacture every protein in its body.
  • The genes in strands of DNA are a storehouse of information, an instruction book.
  • The genes that an organism carries for a particular trait is its genotype and the physical manifestation of the instructions are the organism’s phenotype.
  • Further a gene (a sequence of bases in a section of DNA) affect the phenotype in two main steps.
  • Transcription, in which a copy of a gene’s base sequence is made, and
  • Translation, in which that copy is used to direct the production of a protein.
  • In transcription, the gene’s base sequence or code is copied into a middleman molecule called messenger RNA (mRNA).
  • In translation, the mRNA moves out of the nucleus and into the cytoplasm of the cell, where the messages encoded in the mRNA molecules are used to build proteins.

Image result for CRISPR

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