What is Cas9 protein that is often mentioned in news?

1. A. A molecular scissors used in targeted gene editing
2. B. A biosensor used in the accurate detection of pathogens in patients
3. C. A gene that makes plants pest-resistant
4. D. A herbicidal substance synthesized in genetically modified crops

Answer: A

Explanation

CRISPR-Cas9 is a system used by bacterial cells to recognise and destroy viral DNA as a form of adaptive immunity. Using components of the CRISPR system, researchers can remove, add or alter specific DNA sequences in the genome of higher organisms. The gene editing tool has two components — a single-guide RNA (sgRNA) that contains a sequence that can bind to DNA, and the Cas9 enzyme which acts as a molecular scissor that can cleave DNA.