Question

Given below is a diagram of a T-4 bacteriophage. Choose the option that has all the parts correctly labelled.

• A. A - Head, B - Sheath, C - Collar, D - Tail fibre
• B. A - Sheath, B - Head, C - Collar, D - Tail fibre
• C. A - Head, B - Collar, C - Sheath, D - Tail fibre
• D. A - Collar, B - Head, C - Sheath, D - Tail fibre

Answer 1

The correct option is C A - Head, B - Collar, C - Sheath, D - Tail fibre

Bacteriophages are viruses that infect bacteria. The genetic material in them is usually double-stranded DNA. A typical bacteriophage, for example, the T-4 bacteriophage, infects E.coli.
Their general structure comprises of:

• A polyhedral head that consists of the nucleic acid surrounded by a protein coat or capsid.
• A collar present below the head that joins the head with the tail.
• A sheath that is contractile in nature and helps in the delivery of the viral genetic material into the host cell.
• The tail fibres are used to attach to the host cell.