UPSC Express

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.