Correct option is B
Correct Answer: (b)
Explanation: CRISPR–Cas9 technology is derived from an adaptive immune defence system present in bacteria and archaea. In this system, fragments of invading viral DNA are stored within the CRISPR loci and later transcribed into guide RNAs. These guide RNAs direct the Cas9 nuclease to recognize and cleave complementary foreign DNA during subsequent infections. This natural bacterial defence mechanism formed the basis for the development of CRISPR–Cas9 genome editing.
Information Booster
· CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats.
· Cas proteins function as RNA-guided endonucleases.
· The system provides adaptive and heritable immunity in prokaryotes.
· Cas9 introduces site-specific double-stranded DNA breaks.
· The technology has been repurposed for precise genome editing in multiple organisms.
Additional Knowledge
CRISPR–Cas is not associated with immune responses in eukaryotes, nor does it originate from homologous recombination pathways or transposon insertion systems. Its uniqueness lies in RNA-guided DNA targeting, which is distinct from recombination-based repair or transposase-mediated mobility.
