Question

Explain the CRISPR-Cas system in detail.

Answer 1

The CRISPR-Cas system is the immune system of prokaryotic organism. It helps in resisting foreign genetic elements that provides a form of acquired immunity. By degrading foreign nucleic acids, it prevents infection, conjugation and natural transformation that can enter cell.

CRISPR-Cas genome editing techniques have many potential applications in medicine and crop seed enhancement. This unique technique is much faster, cheaper and accurate; and has a wide range of potential applications. It also enables one to edit parts of the genome by removing, adding or altering sections of the DNA sequence.

The CRISPR-Cas system consists of two key molecules Cas 9 and gRNA:

1. Cas9 is an enzyme. This enzyme functions as a pair of molecular scissors which can cut DNA at a specific location in the genome. The Cas9 follows the guide RNA to the same location in DNA sequence and makes a cut across both strands of the DNA.
2. Guide RNA (gRNA) consists of a small piece of pre-designed RNA sequence of 20 bases long. The scaffold binds to DNA and guides Cas9 to the right part of the genome. This makes sure that the Cas9 enzyme cuts at the right point in the genome. They searches and bind to a specific sequence in the DNA.