NEET BIOLOGY

Detailed explanation-1: -The head of bacteriophage T4 is a prolate icosahedron with one unique portal vertex to which the phage tail is attached. The three-dimensional structure of mature bacteriophage T4 head has been determined to 22-Å resolution by using cryo-electron microscopy.

Detailed explanation-2: -The head-to-tail interface is a multiprotein complex that locks the viral DNA inside the phage capsid correctly positioned for egress and that controls its ejection when the viral particle interacts with the host cell receptor.

Detailed explanation-3: -The head and tail of the bacteriophage are constructed from proteins. The head contains the viral DNA and the tail is a hollow tube used to inject a host cell during infection, though not all phages have a tail.

Detailed explanation-4: -The contractile tail of bacteriophage T4 is a molecular machine that facilitates very high viral infection efficiency. Its major component is a tail sheath, which contracts during infection to less than half of its initial length.