Which mechanism does a bacteriophage primarily use to enter a bacterial cell?

• A. It injects its genetic material through the bacterial cell wall using its tail structure.
• B. It is engulfed by the bacterium through endocytosis.
• C. It fuses its viral envelope with the bacterial membrane.
• D. It dissolves the bacterial cell wall and enters as a whole particle.

Answer: (A)

Verified step by step guidance

1. Understand that bacteriophages are viruses that specifically infect bacteria and have a unique structure, often including a head (capsid) containing genetic material and a tail used for attachment and entry.
2. Recognize that bacteria have a rigid cell wall, which prevents typical viral entry methods like fusion or endocytosis that are common in eukaryotic cells.
3. Recall that bacteriophages attach to the bacterial surface using their tail fibers, which recognize specific receptors on the bacterial cell wall.
4. Learn that after attachment, the bacteriophage uses its tail sheath to contract and inject its genetic material (DNA or RNA) through the bacterial cell wall and membrane into the cytoplasm, leaving the capsid outside.
5. Conclude that the primary mechanism of entry is the injection of genetic material through the bacterial cell wall using the tail structure, rather than engulfment, fusion, or whole-particle entry.