What are bacteriophages ?

Virus that infect bacteria .

The correct answer is Option (2) -Virus that infect bacteria .

Bacteriophages, often referred to as phages, are viruses that infect and replicate within bacteria. The term "bacteriophage" is derived from the Greek words "bacteria" and "phagein," which means "to eat." These viruses are composed of genetic material (either DNA or RNA) enclosed in a protein coat called a capsid.

The phage attaches to specific receptors on the surface of the bacterial cell. This interaction is highly specific and depends on the compatibility between viral proteins and bacterial receptors. After attachment, the phage injects its genetic material (DNA or RNA) into the bacterial cell. The protein coat (capsid) may remain outside the bacterial cell.

Once inside the bacterial cell, the phage genetic material takes control of the host's cellular machinery. It directs the synthesis of new viral components, including more copies of the phage genetic material and structural proteins. Newly synthesized phage components are assembled to form complete virions (virus particles). The host bacterial cell is often lysed (broken open), releasing the newly formed phage particles. This process can lead to the death of the bacterial cell.