Parts of Phage T4 - VIRULENT dsDNA Phage,Prolate Icosahedron,Pyramidal Vertex,Whiskers,Tail Fibres

Parts of Phage T4 - VIRULENT dsDNA Phage

	Parts of Phage T4 - VIRULENT dsDNA Phage 1. The head. The head capsid has the form of a prolate icosahedron. The structure has been describe1 as an elongated, bipyrimidal, hexagonal prism. It consists of two 10 faceted equatorial bands with a pyramidal vertex at either end. It is about 95 nm long and 65 nm wide. The head contains DNA, associated cations, several peptides and three internal proteins. The head capsid is made up of about 2,000 similar subunits.
2. Head tail connector. The head tail connector has a collar with attached whiskers (W). The fibres are kept folded around the tail, their midpoints being held by the whiskers. 3.Thetail. The tail consists of a contractile sheath surrounding an inner core or tube. It is about 80 nm long and 18 nm in diameter. The sheath consists of 144 subunits arranged in 24 rings of 6 subunits each. It is connected to the collar at the upper end, and the baseplate at the lower end. The core is a tubular structure 8 om in diameter, with an axial hole of 25A.
4. The baseplate. The baseplate is hexagonal, and has a tailpin or spike at each corner. 5. Tail fibres. From each of the six corners of the baseplate is given off a long thin tail fibre. Each tail fibre is about 130 nm long and 2 om in diameter. It is composed of two different half fibres named A (proximal half fibre) and BC (distal half fibre) for their antigenic properties.
The A half fibre is attached 10' the baseplate, while the BC half fibre has the site for attachment to a host receptor. The tail fibres recognize specific receptor sites on the host cell wan during attachment.

Index >> Bacteriophages - Part One >> Parts of Phage T4 - VIRULENT dsDNA Phage

Parts of Phage T4 - VIRULENT dsDNA Phage