[Campbell Biology P.302] According to the interview, what was the key evidence that led Fran... | Practice Question

According to the interview, what was the key evidence that led Francisco Mojica to realize that CRISPR was a prokaryotic immune system?

  • A: The repeats were palindromic and could form secondary structures.
  • B: The spacer sequences in bacteria matched the DNA of viruses that could no longer infect them.
  • C: The prokaryotes he studied could tolerate very high salt concentrations.
  • D: Similar repeats were found in very distantly-related bacterial species.

Explanation

The interview explicitly states that in 2003, Mojica found a spacer in E. coli identical to a virus sequence, and that strain of E. coli could not be infected by that virus. This direct link between a spacer and resistance to a specific virus was the key insight.