Q26: Which of the following viral symmetry is found in bacterial... - Veterinary Microbiology, Immunology, Pathology & Parasitology - ICAR AIEEA PG Veterinary Science 14 July 2023 Shift-1 Paper | Agrigyan

Bacteriophages (such as T-even phages, T4, lambda) characteristically exhibit binal (complex dual) symmetry. Their structural architecture comprises an icosahedral head containing the double-stranded DNA genome attached to a helical contractile tail sheath terminating in a baseplate and tail fibers. This combination of icosahedral and helical symmetry in the same virion is called binal symmetry.

Option analysis:

• Correct. Binal symmetry combines an icosahedral capsid head with a helical tail sheath.
• Incorrect. Standard phages possess both simultaneously.
• Incorrect. Helical alone describes viruses like TMV or Rhabdoviruses.
• Incorrect. Binal symmetry is the specific precise term.