AP BIOLOGY

Detailed explanation-1: -Bacteria protect themselves from viruses by fragmenting viral DNA with an endonuclease. The endonuclease is also known as restriction enzyme which is a protein that is produced by bacterial cells which leaves DNA at specific sites along with the molecule.

Detailed explanation-2: -Restriction Endonuclease are produced by bacteria against bacteriophage. These enzymes cleave the DNA fragments of the phages at specific sites. This way the foreign DNA is cleaved into several smaller fragments thereby rendering them harmless to the host organism.

Detailed explanation-3: -Bacterial cell is protected by a cell membrane as well as cell wall. The cell wall of bacteria is composed of peptidoglycan that is capable of withstanding different harsh conditions.

Detailed explanation-4: -CRISPR: ↑ CRISPR is an adaptive immune system that bacteria use to fight off viral infections. CRISPR allows bacteria to remember viruses they have seen in the past, and recognize and fight these viruses in the future.