The CRISPR-associated enzyme Cas9 __________ .


a. cuts RNA at a specific nucleotide sequence
b. cuts DNA at a specific nucleotide sequence
c. is likely derived from a bacteriophage
d. All of the above are correct.

Verified step by step guidance

1. Understand the role of CRISPR-Cas9 in genetic engineering and its origin.
2. Recall that CRISPR-Cas9 is a tool used for cutting DNA, not RNA.
3. Consider the mechanism of action of Cas9, which involves recognizing and cutting specific DNA sequences.
4. Evaluate the options: Option a refers to RNA, which is incorrect for Cas9. Option b correctly describes Cas9's function. Option c is incorrect as Cas9 is derived from bacteria, not bacteriophages.
5. Conclude that the correct answer is the one that accurately describes Cas9's function, which is cutting DNA at a specific nucleotide sequence.

Key Concepts

CRISPR-Cas9 System

The CRISPR-Cas9 system is a revolutionary tool in genetic engineering that allows for precise editing of DNA. It consists of a guide RNA that directs the Cas9 enzyme to a specific location in the genome, where Cas9 makes a double-strand break. This system is derived from a bacterial immune response to viruses, enabling targeted modifications in various organisms.

Function of Cas9

Cas9 is an endonuclease enzyme that cuts DNA at specific nucleotide sequences, as determined by the guide RNA. This ability to create double-strand breaks in DNA is crucial for gene editing, as it allows for the insertion, deletion, or replacement of genetic material. Understanding Cas9's mechanism is essential for utilizing it effectively in genetic research and therapy.

Bacteriophage and CRISPR

Bacteriophages are viruses that infect bacteria, and the CRISPR system is believed to have evolved as a defense mechanism against these phages. The presence of sequences in CRISPR that match bacteriophage DNA suggests a co-evolutionary relationship. This connection highlights the origins of the CRISPR-Cas9 system and its application in modern biotechnology.