Question

naturally in plant pathogens has crRNAs with "protospacer" regions complementary to the foreign DNA crRNAs hybridize to tracr RNAs (also encoded by CRISPR system) and this pair associates w the Cas9 nuclease to recognize and cut both strands of DNAs

Answer 1

CRISPR/Cas system is a mechanism in prokaryotes for adaptive immune defense against viral DNA, which has been adapted for precise gene editing and correction of heritable diseases.

Step-by-step explanation:

The CRISPR/Cas system is an immune mechanism in prokaryotes that provides adaptive immunity by using CRISPR sequences paired with CRISPR-associated (Cas) proteins to detect and destroy invading viral DNA. Upon phage infection, spacer RNA molecules derived from previous phage attacks guide the Cas9 protein to the complementary region of the invading phage DNA. The Cas9 protein then cleaves the viral DNA, thereby preventing infection. This system not only offers defense against current infections but also remembers past infections and passes this adaptive immunity to subsequent generations.

Use of the CRISPR/Cas system has been adapted for gene editing to cut DNA at specific nucleotide sequences. This has allowed for a wide range of applications including the correction of genes responsible for heritable diseases and other forms of genome engineering. The knowledge that CRISPR sequences are also found in the human genome has propelled this technology to the forefront, earning it recognition as the 'Breakthrough of 2015' in the field of genetic engineering.