Question

What are the three steps of CRISPR-Cas mediated antiviral defense?

Answer 1

CRISPR-Cas mediated antiviral defense involves three steps: recognition of the viral DNA, target binding and interference, and memory formation.

Step-by-step explanation:

CRISPR-Cas mediated antiviral defense involves three steps:

1. The first step is the recognition of the viral DNA. When viral DNA enters a prokaryotic cell, the CRISPR loci in the genome are transcribed and processed into small CRISPR RNAs (crRNAs). These crRNAs then bind to the Cas proteins.
2. The second step involves target binding and interference. The crRNA-Cas protein complex recognizes and binds to the viral DNA by base pairing between the crRNA and the target DNA sequence. This binding activates the Cas proteins to cut the viral DNA, leading to its degradation.
3. The third step is the memory formation. During the process, a small fragment of the viral DNA is incorporated into the CRISPR locus as a spacer. This allows the prokaryotic cell to remember the viral sequence and mount a faster and more efficient defense if it is encountered again in the future.