Question

Which is an endonuclease in CRISPR Cas9 Technique?

• A. gRNA
• B. Cas 9
• C. PAM
• D. Cr RNA

Hint:

• CRISPR-Cas9 System Components
  • Cas9 Protein An RNA-guided DNA endonuclease (enzyme that cuts DNA).
  • Guide RNA (gRNA/sgRNA) Directs Cas9 to the target DNA sequence. Contains a crRNA-like spacer for target recognition and a tracrRNA-like scaffold for Cas9 binding.
• PAM Sequence A short sequence in the target DNA, adjacent to the target site, required for Cas9 recognition and cleavage. Not part of the Cas9 enzyme or gRNA.

Answer 1

The Correct Option is B

In the CRISPR Cas9 technique, the Cas9 protein functions as an endonuclease. Endonucleases are enzymes that cleave the phosphodiester bonds within a nucleic acid strand. In the CRISPR system, the Cas9 protein specifically introduces double-strand breaks in DNA at locations determined by a guide RNA (gRNA). Here's a breakdown of the roles of each component:

• gRNA (guide RNA): A molecule that directs the Cas9 enzyme to the specific DNA sequence to be cut.
• Cas9: The protein acting as an endonuclease by making specific cuts in the DNA sequence.
• PAM (Protospacer Adjacent Motif): A DNA sequence necessary for the binding of the Cas9 and initiation of cleavage.
• Cr RNA (CRISPR RNA): Part of the gRNA molecule that is complementary to the target DNA sequence.

Considering these descriptions, Cas 9 is the component with endonuclease activity in the CRISPR Cas9 system.